xtensa: add __NR_syscalls along with __NR_syscall_count

__NR_syscall_count macro holds the number of system call
exist in xtensa architecture. We have to change the value
of __NR_syscall_count, if we add or delete a system call.

One of the patch in this patch series has a script which
will generate a uapi header based on syscall.tbl file.
The syscall.tbl file contains the total number of system
calls information. So we have two option to update __NR-
_syscall_count value.

1. Update __NR_syscall_count in asm/unistd.h manually by
   counting the no.of system calls. No need to update __NR-
   _syscall_count until we either add a new system call or
   delete existing system call.

2. We can keep this feature it above mentioned script,
   that will count the number of syscalls and keep it in
   a generated file. In this case we don't need to expli-
   citly update __NR_syscall_count in asm/unistd.h file.

The 2nd option will be the recommended one. For that, I
added the __NR_syscalls macro in uapi/asm/unistd.h.
The macro __NR_syscalls also added for making the name
convention same across all architecture. While __NR_syscalls
isn't strictly part of the uapi, having it as part of the
generated header to simplifies the implementation. We also
need to enclose this macro with #ifdef __KERNEL__ to avoid
side effects.

Signed-off-by: Firoz Khan <firoz.khan@linaro.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
[Max: Drop __NR_syscall_count completely, use __NR_syscalls instead]

arch/xtensa/include/uapi/asm/unistd.h

@@ -778,7 +778,9 @@ __SYSCALL(350, sys_pkey_free, 1)
 #define __NR_statx				351
 __SYSCALL(351, sys_statx, 5)
 
-#define __NR_syscall_count			352
+#ifdef __KERNEL__
+#define __NR_syscalls				352
+#endif
 
 /*
  * sysxtensa syscall handler

arch/xtensa/kernel/entry.S

@@ -1874,7 +1874,7 @@ ENTRY(system_call)
 	/* syscall = sys_call_table[syscall_nr] */
 
 	movi	a4, sys_call_table
-	movi	a5, __NR_syscall_count
+	movi	a5, __NR_syscalls
 	movi	a6, -ENOSYS
 	bgeu	a3, a5, 1f
 

arch/xtensa/kernel/syscall.c

@@ -30,8 +30,8 @@
 
 typedef void (*syscall_t)(void);
 
-syscall_t sys_call_table[__NR_syscall_count] /* FIXME __cacheline_aligned */= {
-	[0 ... __NR_syscall_count - 1] = (syscall_t)&sys_ni_syscall,
+syscall_t sys_call_table[__NR_syscalls] /* FIXME __cacheline_aligned */= {
+	[0 ... __NR_syscalls - 1] = (syscall_t)&sys_ni_syscall,
 
 #define __SYSCALL(nr,symbol,nargs) [ nr ] = (syscall_t)symbol,
 #include <uapi/asm/unistd.h>