asiliantfb: fix test of unsigned in asiliant_calc_dclk2()

Ftarget, Fret, n and m are unsigned so the tests did not work.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Andres Salomon <dilinger@debian.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>