cxl: Remove dead Kconfig options

The CXL_AFU_DRIVER_OPS and CXL_LIB Kconfig options were added to coordinate
merging of new features. They no longer serve any purpose, so remove them.

Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200602040341.10152-1-ajd@linux.ibm.com