sm750fb/sm750_hw.c: fixed comments

Fixed multiline comments to meet style standards,
fixed typos and split comment lines over 80 characters.

Signed-off-by: Stefan Wolz <wolzstefan@web.de>
Signed-off-by: Christian Halder <christian.halder@fau.de>
Signed-off-by: Sebastian Handwerker <sebastian.handwerker@posteo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>