Staging: dt3155_isr: cleanup fbuffer usage

Now that dt3155_drv.c is not dependent on the global symbol
dt3155_fbuffer[], declared in dt3155_isr.c, remove it.

This also fixes many of the coding style problems in dt3155_isr.c.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Scott Smedley <ss@aao.gov.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>