tty: serial: meson: merge the two register sections for AML_UART_CONTROL

In the code there are two separate sections which each describe some of
the bits in the AML_UART_CONTROL register.
Merge these into one section to make the code easier to read.
No functional changes intended.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>