rt2x00: rt2800lib: remove TXMIXER_GAIN entries from the extended EEPROM map

The comments are indicating that the TXMIXER_GAIN_BG
and TXMIXED_GAIN_A entries are overlapping with the
RSSI_BG2 and RSSI_A2 entries in the extended EEPROM
map. This is not correct, because the upper byte of
the RSSI_BG2 and RSSI_A2 entries are reserved. There
are no TX mixer gain values are stored at all in the
extended EEPROM.

Remove the initialization of these entries from the
extended EEPROM map to reflect this.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Acked-by: Paul Menzel <paulepanter@users.sourceforge.net>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: John W. Linville <linville@tuxdriver.com>