mfd: use shorter set_current_state()

Since this routine declares a separate "tsk" pointer for no other reason than
to call set_task_state(), get rid of it and just invoke set_current_state().

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Nicolas Pitre <nico@cam.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>