media: am437x-vpfe: fix function trace debug log

checkpatch.pl nows reports several:
WARNING: Prefer using '"%s...", __func__' to using '<function name>',
this function's name, in a string.

So fix these for the whole driver.
At the same time remove the function entry trace log as those can be
enabled using ftrace instead.

Signed-off-by: Benoit Parrot <bparrot@ti.com>
Acked-by: Lad Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>