arm64: assembler: remove inherit_daif macro

We haven't needed the inherit_daif macro since commit:

  ed3768db ("arm64: entry: convert el1_sync to C")

... which converted all callers to C and the local_daif_inherit
function.

Remove the unused macro.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>