arm64: avoid prototype warnings for syscalls

arm64: avoid prototype warnings for syscalls

With W=1 warnings enabled, there are lots of complaints about
missing prototypes for system calls, plus a few other related
ones:

arch/arm64/kernel/sys_compat.c:68:6: error: no previous prototype for 'compat_arm_syscall' [-Werror=missing-prototypes]
arch/arm64/include/asm/syscall_wrapper.h:76:32: error: no previous prototype for '__arm64_sys_io_setup' [-Werror=missing-prototypes]
arch/arm64/include/asm/syscall_wrapper.h:41:32: error: no previous prototype for '__arm64_compat_sys_io_setup' [-Werror=missing-prototypes]
arch/arm64/include/asm/syscall_wrapper.h:76:32: error: no previous prototype for '__arm64_sys_io_destroy' [-Werror=missing-prototypes]
arch/arm64/include/asm/syscall_wrapper.h:76:32: error: no previous prototype for '__arm64_sys_io_submit' [-Werror=missing-prototypes]

Add declarations to the syscall macros to avoid all of these, plus
one for the compat syscall entry.

Signed-off-by: Arnd Bergmann <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Acked-by: Ard Biesheuvel <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>