parisc: add __NR_syscalls along with __NR_Linux_syscalls

parisc: add __NR_syscalls along with __NR_Linux_syscalls

__NR_Linux_syscalls macro holds the number of system call
exist in parisc architecture. We have to change the value
of __NR_Linux_syscalls, 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-
_Linux_syscalls value.

1. Update __NR_Linux_syscalls in asm/unistd.h manually by
   counting the no.of system calls. No need to update __NR-
   _Linux_syscalls 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_Linux_syscalls 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 along
with __NR_Linux_syscalls asm/unistd.h. The macro __NR_sys-
calls 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>
Acked-by: Helge Deller <deller@gmx.de>
Signed-off-by: Helge Deller <deller@gmx.de>