systemd-udevd substitutes variables starting with $ in the PROGRAM
argument. If a shell variable is to be used, two $ need to be used to
escape properly. This fixes three instances of the following warning:
Invalid value "..." for PROGRAM (char 58: invalid substitution type), ignoring, but please fix it.
The to symlink serial0/1 currently might apply to the first or second
ttyAMAX instance. In downstream, a patch makes sure that the first
PL011 is always ttyAMA0. However, upstream the numbering depends on the
UART alias, which leads to the first PL011 being ttyAMA1.
Check the actual iobase too to make sure we are dealing with the first
PL011 instance.
See also:
05cfe136f7 (diff-2678c183f503319c8d8c09c818af789a)
