meson_uart: enabling the core clock for uart_A

[Helmut Klein]

Hallo Carlo,

the u-boot of my s905 based media player (netxeon minimx, p200 
compatible) doesn't enable the core clock for uart_A. therefore my 
bluetooth adapter, which is connected to this device, isn't operational.

i've added some lines, extracted from amlogic's driver, to meson_uart.c 
and modified the clock header files, to be able to add the core clock 
info to the dtb.

May i send you the patches?

if yes, which git tree should i use as the base?

regards
Helmut