Revert "regmap: allow to define reg_update_bits for no bus configuration"

This reverts commit 758c6799 which is
commit 02d6fdecb9c38de19065f6bed8d5214556fd061d upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I4a8c202a4ad8b3640b02d417a12c4a8d2d2d62e1
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>