mfd: wcd9xxx: Print all the values while debugging

The codec register read/write functions print out the address and data of
registers.  So far it prints only the first byte of data regardless of
requested read/write data length.  Enhance debugging output to show all
bytes for better debugging support.

Change-Id: I7e38493e1ad041ed274a66d1f0cee7f70e8b1e85
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>