misc: xilinx_sdfec: fix xsdfec_poll()'s return type

misc: xilinx_sdfec: fix xsdfec_poll()'s return type

xsdfec_poll() is defined as returning 'unsigned int' but the
.poll method is declared as returning '__poll_t', a bitwise type.

Fix this by using the proper return type and using the EPOLL
constants instead of the POLL ones, as required for __poll_t.

CC: Derek Kiernan <derek.kiernan@xilinx.com>
CC: Dragan Cvetic <dragan.cvetic@xilinx.com>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Acked-by: Dragan Cvetic <dragan.cvetic@xilinx.com>
Link: https://lore.kernel.org/r/20191209213655.57985-1-luc.vanoostenryck@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>