clk: at91: sama7g5: s/ep_chg_chg_id/ep_chg_id

s/ep_chg_chg_id/ep_chg_id in documentation of master clock structure.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20230615093227.576102-12-claudiu.beznea@microchip.com