Fix cast warnings
VCHIQ: Use unsigned integers for unsigned values

The VCHIQ interface used signed integers for values which are
inherently unsigned. Worse, the parameter validation code treated them
as if they were unsigned, checking for overflow but not underflow.

This patch converts those integers to unsigned integers.

Thanks to Jann Horn.
Merge in arm: mm: lockless get_user_pages_fast support and use with vchiq
Remove legacy bcm2708 MMC driver
Add quick config.

This is designed for quick compiling when developing.
No modules are needed and it includes all Pi specific drivers
Remove duplicated BCM2708 driver
MMC dma is not experimental