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

This reverts commit fbddd48f which is
commit 02d6fdec 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: I3a0035e1ad34dee35d3bd5d1a061c2a52e234f2a
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>