clk: at91: sama7g5: allow SYS and CPU PLLs to be exported and referenced in DT

Allow SYSPLL and CPUPLL to be referenced as a PMC_TYPE_CORE clock
from phandle in DT.

Suggested-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
[claudiu.beznea@microchip.com: adapt commit message, add CPU PLL]
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/1605800597-16720-4-git-send-email-claudiu.beznea@microchip.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>