staging: r8188eu: rf_chip is constant

For this driver, rf_chip is always RF_6052. Remove the rf_chip component
from struct hal_data_8188e and resulting dead code.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211111212644.9011-5-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>