staging: rtl8192u: rename general variables in r819xU_phy.c

This patch renames the following variables:
- dwRegAddr and RegAddr into reg_addr
- dwData and Data       into data
- BitShift              into bitshift
- Offset                into offset
- NewOffset             into new_offset
- Bandwidth             into bandwidth

The renaming was done to remove camel case and
unnecessary 'dw' prefix from the above variable names.

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>