V4L/DVB: dib3000mc: reduce large stack usage

This patch reduces static stack usage of one of the 2 top offenders
as listed by 'make checkstack':

Building with CONFIG_FRAME_WARN=2048 produces:

drivers/media/dvb/frontends/dib3000mc.c:853: warning: the frame size of 2224 bytes is larger than 2048 bytes

and in 'make checkstack', the stack usage goes from:
0x00000bbd dib3000mc_i2c_enumeration [dib3000mc]:	2232
to unlisted with this patch.

I don't have the hardware that is needed to test this patch.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Patrick Boettcher <pboettcher@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>