staging: rtl8188eu: fold rtl8188e_read_chip_version() into rtl8188e_SetHalODMVar()

Both rtl8188e_read_chip_version() and ReadChipVersion8188E() are used
only in one place.  Make ReadChipVersion8188E() a void function and
eliminate its wrapper - rtl8188e_read_chip_version().

Signed-off-by: Jakub Sitnicki <jsitnicki@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>