staging: vt6656: Use fls instead of for loop in vnt_update_top_rates

staging: vt6656: Use fls instead of for loop in vnt_update_top_rates

Replace the for loops of the vnt_update_top_rates function by the fls
function.

The purpose of the two for loops is to find the most significant bit set
in a range of bits. So, they can be replace by the fls function (find
last set) with a previous mask to define the range.

This way avoid the iteration over unnecessary for loops.

The header "linux/bits.h" can be remove as it is included in the header
"linux/bitops.h".

Signed-off-by: Oscar Carter <oscar.carter@gmx.com>
Link: https://lore.kernel.org/r/20200420155246.4925-1-oscar.carter@gmx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>