Driver SDIO code uses helper functions to do IO to the SDIO
device. Current helpers handle IO of a single byte as well as
multi-byte. Driver predominately uses single byte IO. If the
common case is made simple it simplifies the whole driver. The common
case can be made simple by splitting the multi-byte and single byte
calls into separate functions, i.e 4 functions in total, read single
byte, read multi-byte, write single byte, write multi-byte.

Also, we need to handle the debug code. Currently debug calls after
read/write fail access the IO buffer. This buffer, at best, does not hold
useful data on the error path, at worst is uninitialized and holds
garbage.

Split read/write helper functions into two functions each, one for
single byte IO and one for multi-byte IO. Fix all call sites. Do not
change the program logic.
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>