cpu: at91: add compatible for ARM9260EJ-S

The crystal, CPU and master clock were not displayed correctly on SAM9X60
after adding CCF clock support. Add compatible for ARM926EJ-S to fix
this.

Reported-by: Eugen Hristev <eugen.hristev@microchip.com>
Fixes: a6486228 ("clk: at91: sam9x60: add support compatible with CCF")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>