powerpc: Unsigned speed cannot be negative in udbg_16559.c
powerpc: Unsigned speed cannot be negative in udbg_16559.c

"unsigned int" speed cannot be negative, it's thus pointless
to test if it is.

Signed-off-by: Roel Kluin <aa9c6213291cec1ff07688554fb7b904b9ffe4e3@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <a7089bb6e7e92505d88aaff006cbdd60cc9120b6@kernel.crashing.org>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas