ANDROID: trusty-ipc: fix tipc_poll()

In recent kernels, implementations of file_operations::poll() are
supposed to return __poll_t and use the EPOLL* constants, not POLL*.

This fixes the following 'sparse' warning:

    drivers/trusty/trusty-ipc.c:1564:27: warning: incorrect type in initializer (different base types)
    drivers/trusty/trusty-ipc.c:1564:27:    expected restricted __poll_t ( *poll )( ... )
    drivers/trusty/trusty-ipc.c:1564:27:    got unsigned int ( * )( ... )

Also, on some architectures the EPOLL* constants are different from the
POLL* ones; see upstream commit a9a08845 ("vfs: do bulk POLL* ->
EPOLL* replacement").

Change-Id: Ie014a57a0b1405b7f69cb4936a2962fea084c78c
Signed-off-by: Eric Biggers <ebiggers@google.com>