clk: at91: clk-master: improve readability by using local variables

Improve readability in clk_sama7g5_master_set() by using local
variables.

Suggested-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-6-claudiu.beznea@microchip.com


Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>