rtl8xxxu: Remove unneeded 8192eu hack

This removes an unneeded hack for 8192eu, and allows for initializing
REG_FPGA0_XAB_RF_SW_CTRL at the same point as it is done for all other
parts.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>