ARM: keystone: dts: fix netcp clocks and add names

Fix the pa clock to point to the clkpa which has clock rate of 1/3 of PA
PLL clock and add clock names.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>