n_gsm: clean up printks

[Original From Ken Mills but I redid it using pr_ helpers instead]

Also fix up coding style, there are two warnings left but that is where
the CodingStyle tools blow up because they cannot handle

	if (blah) {
		foo
	} else switch (x) {
		case 1:
		}

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>