arm64: lockdep: enable checks for held locks when returning to userspace

arm64: lockdep: enable checks for held locks when returning to userspace

Currently arm64 doesn't use CONFIG_GENERIC_ENTRY and doesn't call
lockdep_sys_exit() when returning to userspace.
This means that lockdep won't check for held locks when
returning to userspace, which would be useful to detect kernel bugs.

Call lockdep_sys_exit() when returning to userspace,
enabling checking for held locks.

At the same time, rename arm64's prepare_exit_to_user_mode() to
exit_to_user_mode_prepare() to more clearly align with the naming
in the generic entry code.

Signed-off-by: Eric Chan <ericchancf@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230531090909.357047-1-ericchancf@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>