sunxi: clk: add basic clocks for A83T

Add basic clocks pll1, pll5, and some default values from allwinner u-boot.

Signed-off-by: Vishnu Patekar <vishnupatekar0510@gmail.com>
[hdegoede@redhat.com] Fix PLL6 init to run at 600 MHz instead of 288 MHz,
fixing the mmc support not working
[hdegoede@redhat.com] Fix PLL init code to properly wait for the PLL-s to
stabilize, fixing cold-booting directly from sdcard not working
Signed-off-by: Hans de Goede <hdegoede@redhat.com>