ARM64: dts: meson-axg: uart: drop legacy compatible name from EE UART

When update the clock info for the UART controller in the EE domain,
the driver explicitly require 'pclk' in order to work properly.

With current logic of the code, the driver will go for the legacy clock probe
routine if it find current compatible string match to 'amlogic,meson-uart',
which result in not requesting the 'pclk' clock, thus break the driver in the end.

Acked-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>