s390: ptrace: hard-code "s390x" instead of UTS_MACHINE

s390 uses the UTS_MACHINE defined arch/s390/Makefile as follows:

  UTS_MACHINE     := s390x

We do not need to pass the fixed string from the command line.
Hard-code user_regset_view::name, like many other architectures do.

Link: https://lkml.kernel.org/r/20200413013113.8529-1-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/Makefile

@@ -33,11 +33,6 @@ CFLAGS_stacktrace.o	+= -fno-optimize-sibling-calls
 CFLAGS_dumpstack.o	+= -fno-optimize-sibling-calls
 CFLAGS_unwind_bc.o	+= -fno-optimize-sibling-calls
 
-#
-# Pass UTS_MACHINE for user_regset definition
-#
-CFLAGS_ptrace.o		+= -DUTS_MACHINE='"$(UTS_MACHINE)"'
-
 obj-y	:= traps.o time.o process.o base.o early.o setup.o idle.o vtime.o
 obj-y	+= processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o
 obj-y	+= debug.o irq.o ipl.o dis.o diag.o vdso.o

arch/s390/kernel/ptrace.c

@@ -1416,7 +1416,7 @@ static const struct user_regset s390_regsets[] = {
 };
 
 static const struct user_regset_view user_s390_view = {
-	.name = UTS_MACHINE,
+	.name = "s390x",
 	.e_machine = EM_S390,
 	.regsets = s390_regsets,
 	.n = ARRAY_SIZE(s390_regsets)