rt2x00: rt2800lib: adjust frequency offset for RF3053

Along with other chipsets, the Ralink driver uses the
frequency adjustment code for RF3053 as well. Remove
the bogus place-holder comment from the RF3053 specific
channel configuration function and call the frequency
adjustment function instead

Based on the DPO_RT5572_LinuxSTA_2.6.0.1_20120629
driver.

Reference:
  RT3593_ChipSwitchChannel function in chips/rt3593.c

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>