clk: at91: do not compile dt-compat.c for sama7g5 and sam9x60

There is no need to have dt-compat.c compiled for SAMA7G5 and SAM9X60
as there is no in kernel device tree that could use it. Thus avoid
compiling dt-compat.c for them.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20221208114515.35179-4-claudiu.beznea@microchip.com