Combine modem-qcom-msm-{mainline,downstream}-common to a single APKBUILD
with mainline and downstream subpackages.
Enable rmtfs service here instead of directly in the package.
[ci:skip-vercheck]: for qrtr version fix
At the moment, only "modem" is detected as rpmsg name.
On MSM8916 the audio DSP and modem are both on the same remote
processor ("hexagon").
Add it to the udev rule so the modem symlink is created on MSM8916.
On my device the rpmsg0 have DATA5_CNTL under name attribute instead of
rpmsg_name
```
looking at device '/devices/platform/smd/smd:modem/smd:modem.rpmsg_chrdev.0.0/rpmsg/rpmsg_ctrl1/rpmsg0':
KERNEL=="rpmsg0"
SUBSYSTEM=="rpmsg"
DRIVER==""
ATTR{dst}=="0"
ATTR{src}=="0"
ATTR{name}=="DATA5_CNTL"
```
So check for name instead of rpmsg_name.
Add modem-qcom-msm-downstream-common package that pulls in the
dependencies.
qcom_rmtfs now has udev rules to find the storage partitions. My hope
is they can be written flexibly enough to cover all devices and kernel
flavors.
