ARM: 9110/1: oabi-compat: fix oabi epoll sparse warning

As my patches change the oabi epoll definition, I received a report
from the kernel test robot about a pre-existing issue with a mismatched
__poll_t type.

The OABI code was correct when it was initially added in linux-2.16,
but a later (also correct) change to the generic __poll_t triggered a
type mismatch warning from sparse.

As __poll_t is always 32-bit bits wide and otherwise compatible, using
this instead of __u32 in the oabi_epoll_event definition is a valid
workaround.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 8ced390c ("define __poll_t, annotate constants")
Fixes: ee219b94 ("uapi: turn __poll_t sparse checks on by default")
Fixes: 687ad019 ("[ARM] 3109/1: old ABI compat: syscall wrappers for ABI impedance matching")
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>