rt2x00: rt2800lib: rename rt2800_init_bbb_early to rt2800_init_bbp_early

The function is used for BBP register initialization,
fix the typo in the function name to reflect that.

The patch contains no functional changes.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>