[media] saa7134-i2c: make debug macros to use pr_fmt()

Converting debug prints to use pr_foo() is not trivial, as the
result will be a way worse than what's provided here, due to the
pieces of the code that prints the I2C transfers. Those use a
lot pr_cont(), and, depending on using either level 1 or 2,
a different set of macros are selected.

So, let's replace d1printk() and d2printk() macros by i2c_dbg()
and i2c_count() adding a debug level there.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>