BACKPORT: arm64: vdso: Remove stale files from old assembly implementation

Moving over to the generic C implementation of the vDSO inadvertently
left some stale files behind which are no longer used. Remove them.

Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
(cherry picked from commit 37a5076098c17f40913c772b017ff8e48e449656)
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 154668398
Change-Id: Ia1a962ae8ef42413e2c5dfd7c9af57d928dbeecf