arm64: kuser32-bit helpers: dont include unistd32.h

While building lsk-3.10-android branch, we run into a series
of build warnings for arm64 arch:
----------
In file included from arch/arm64/kernel/kuser32.S:32:0:
arch/arm64/include/asm/unistd32.h:24:0: warning: "__NR_restart_syscall" redefined
 #define __NR_restart_syscall 0
 ^
In file included from include/asm-generic/unistd.h:1:0,
                 from arch/arm64/include/uapi/asm/unistd.h:16,
                 from arch/arm64/include/asm/unistd.h:50,
                 from arch/arm64/kernel/kuser32.S:31:
include/uapi/asm-generic/unistd.h:390:0: note: this is the location of the previous definition
 #define __NR_restart_syscall 128
 ^
In file included from arch/arm64/kernel/kuser32.S:32:0:
arch/arm64/include/asm/unistd32.h:26:0: warning: "__NR_exit" redefined
 #define __NR_exit 1
 ^
In file included from include/asm-generic/unistd.h:1:0,
                 from arch/arm64/include/uapi/asm/unistd.h:16,
                 from arch/arm64/include/asm/unistd.h:50,
                 from arch/arm64/kernel/kuser32.S:31:
include/uapi/asm-generic/unistd.h:292:0: note: this is the location of the previous definition
 #define __NR_exit 93
 ^
----------

This fix removes asm/unitstd32.h include to avoid duplication of
"__NR_" syscall definitions. It is based on mainline commit:
f3e5c847ec "arm64: Add __NR_* definitions for compat syscalls".

The corresponding change in AOSP (commit: cfc7e99e9e, "arm64: Add..")
seem to be the early version or backport of the above mainline
commit to aosp/android-3.10. The only difference between mainline and
aosp commit is that the latter didn't have to deal with that
problematic include because it is not present in aosp/android-3.10
unlike mainline or lsk-v3.10-android tree.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

arch/arm64/kernel/kuser32.S

@@ -29,7 +29,6 @@
  */
 
 #include <asm/unistd.h>
-#include <asm/unistd32.h>
 
 	.align	5
 	.globl	__kuser_helper_start