seccomp: Get compat syscalls from asm-generic header

seccomp: Get compat syscalls from asm-generic header

Move retrieval of compat syscall numbers into inline function defined in
asm-generic header so that arches may override it.

[[email protected]: Resolve merge conflict.]

Suggested-by: Paul Burton <[email protected]>
Signed-off-by: Matt Redfearn <[email protected]>
Acked-by: Kees Cook <[email protected]>
Cc: [email protected]
Cc: Arnd Bergmann <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Will Drewry <[email protected]>
Cc: [email protected]
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/12978/
Signed-off-by: Ralf Baechle <[email protected]>