media: m88ds3103: drop reg11 calculus from m88ds3103b_select_mclk()

This value is never used at the code. So, drop it.

Solves a W=1 clang warning.

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>