Revert "drm: atmel-hlcdc: enable sys_clk during initalization."

This reverts commit d2c755e66617620b729041c625a6396c81d1231c
("drm: atmel-hlcdc: enable sys_clk during initalization."). With
commit "drm: atmel-hlcdc: enable clock before configuring timing engine"
there is no need for this patch. Code is also simpler.

Cc: Sandeep Sheriker Mallikarjun <sandeepsheriker.mallikarjun@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1576672109-22707-7-git-send-email-claudiu.beznea@microchip.com