mmc: mvsdio: use dev_*() API instead of pr_*() API

The mvsdio driver was already using some dev_*() functions to print
some messages, but still using pr_*() functions for some others. This
patch converts all messages to use dev_*() functions.

Many of the pr_*() function calls were printing the output of
mmc_hostname() to preprend the message with an identifier for the
device. Since the dev_*() functions do that automatically, this patch
also gets rid of those string prefixes.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Chris Ball <cjb@laptop.org>