arm64: move PAC masks to <asm/pointer_auth.h>

Now that we use XPACLRI to strip PACs within the kernel, the
ptrauth_user_pac_mask() and ptrauth_kernel_pac_mask() definitions no
longer need to live in <asm/compiler.h>.

Move them to <asm/pointer_auth.h>, and ensure that this header is
included where they are used.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Amit Daniel Kachhap <amit.kachhap@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kristina Martsenko <kristina.martsenko@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230412160134.306148-4-mark.rutland@arm.com


Signed-off-by: Will Deacon <will@kernel.org>