- Add bcm2835_mbox_property for generic property request, it accepts
pointer to prepared property chan message and its size, forwards
it to MBOX and copies result back
- Make all bcm2835_mbox_XXX functions that use property channel go
through bcm2835_mbox_property path. Do not accept device_t as
an argument, it's not required: all DMA operatiosn should go
through mbox device, and all API consumers should report errors
on their side.
BCM2835_MBOX_CHAN_PROP channel. The old channel (BCM2835_MBOX_CHAN_FB)
seems deprecated on recent firmware versions and is causing a freeze on
RPi 2.
The actual changes in the framebuffer drivers will follow in subsequent
commits.
to get the default frequency of the sdhci device.
While here use a u_int to hold the frequency as it may be too large to fit
in a 32-bit signed integer. This is the case when we have a 250MHz clock.
