mwl8k: replace rateinfo bitfields with mask and shift macros
mwl8k: replace rateinfo bitfields with mask and shift macros

AFAICT, this driver is claiming that 24 bits of rate info fit into a
16-bit field in the Tx descriptor.  Anyway, the use of bitfields is
frowned-upon for a variety of well-documented reasons...

Signed-off-by: John W. Linville <2a53bac7a5d324865ef46ec4c38b2c0fba1456b4@tuxdriver.com>

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