media: dvb-frontends: remove extraneous parens

Fixes 2 warnings from Clang about extra parentheses in a conditional,
that might have been meant as assignment.

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>