V4L/DVB (4411): Fix minor errors in build files

In pwc Kconfig, change 'depends' to 'depends on'
In dvb-core Makefile, change '=' to ':='

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>