canby_pins: enable pinmux for pwm4 and pwm7

Signed-off-by: Steve Sakoman <steve@sakoman.com>
canby: enable led driver for pwm4 and pwm7

This patch also removes the code to set up pwm0 and pwm1
since control of those pwm's is hard coded in the lcd
panel driver.

Despite the name "led driver", on Canby this driver is used
to generate a beeper tone and control the volume of the
tone.

Signed-off-by: Steve Sakoman <steve@sakoman.com>
leds-mxs-pwm: add hw accelerated LED blink support to driver

Signed-off-by: Steve Sakoman <steve@sakoman.com>