fs/eventpoll.c: fix spelling

eventpoll.c has wonderful comments but some annoying typos
sneaked in:
	* toepoll_ctl -> to epoll_ctl
	* rapresent -> represents
	* sructure -> structure
	* machanism -> mechanism
	* trasfering -> transferring

Signed-off-by: Daniel Baluta <daniel.baluta@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>