[PARISC] Use symbolic last syscall in __NR_Linux_syscalls

Hopefully will prevent people from forgetting to update this...

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

include/asm-parisc/unistd.h

@@ -793,7 +793,7 @@
 #define __NR_statfs64		(__NR_Linux + 298)
 #define __NR_fstatfs64		(__NR_Linux + 299)
 
-#define __NR_Linux_syscalls     300
+#define __NR_Linux_syscalls     (__NR_fstatfs64 + 1)
 
 #define HPUX_GATEWAY_ADDR       0xC0000004
 #define LINUX_GATEWAY_ADDR      0x100