From i.MX6SL Reference Manual, the PWMx's ipg clock
for registers access is from perclk, correct them.
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>