staging: r8188eu: remove sdio definitions

The r8188eu chipset is connected via usb. We don't need the register
and bit field definitions for the sdio interface.

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220704145221.159949-5-martin@kaiser.cx


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