Staging: bcm: signedness bug in StoreSFParam()

wrm() returns negative error codes so "ret" needs to be signed here.
There was place where wrm() returned positive EACCES instead of
negative -EACCES so I fixed that as well.  Also a few checkpatch.pl
issues.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>