misc: introduce Qcom GENI wrapper

misc: introduce Qcom GENI wrapper

Qualcomm peripherals like UART, SPI, I2C, etc are all exposed under a
common GENI Serial Engine wrapper device. Replace the stub driver we use
for this currently with a full-on misc device and implement support for
loading peripheral firmware.

Each of the peripherals has it's own protocol-specific firmware, this is
stored on the internal storage of the device with a well-known partition
type GUID.

To support this, GENI will bind peripherals in two stages. First the
ones that already have firmware loaded (such as the serial port) are
bound in the typical way. But devices that require firmware loading are
deferred until EVT_LAST_STAGE_INIT. At this point we can be sure that
the storage device is available, so we load the firmware and then bind
and probe the remaining children.

Child devices are expected to determine if firmware loading is necessary
and call qcom_geni_load_firmware().

Since Linux currently doesn't support loading firmware (and firmware may
not be available), we probe all GENI peripherals to ensure that they
always load firmware if necessary.

Signed-off-by: Casey Connolly <casey.connolly@linaro.org>
Link: https://patch.msgid.link/20250714-geni-load-fw-v5-3-5abbc0d29838@linaro.org
Signed-off-by: Casey Connolly <kcxt@postmarketos.org>