powerpc: Standardise on NR_syscalls rather than __NR_syscalls.

Most architectures use NR_syscalls as the #define for the number of syscalls.

We use __NR_syscalls, and then define NR_syscalls as __NR_syscalls.

__NR_syscalls is not used outside arch code, whereas NR_syscalls is. So as
NR_syscalls must be defined and __NR_syscalls does not, replace __NR_syscalls
with NR_syscalls.

Signed-off-by: Rashmica Gupta <rashmicy@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/vdso64/datapage.S

@@ -62,7 +62,7 @@ V_FUNCTION_BEGIN(__kernel_get_syscall_map)
 	cmpli	cr0,r4,0
 	crclr	cr0*4+so
 	beqlr
-	li	r0,__NR_syscalls
+	li	r0,NR_syscalls
 	stw	r0,0(r4)
 	blr
   .cfi_endproc