arm64: vdso32: add ARM.exidx* sections

These show up when building with clang+lld.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20220628151307.35561-2-joey.gouly@arm.com


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