bcm2835_vcbus: add compatibility name for ^/sys/contrib/vchiq

It's unclear how this didn't get caught in my last iteration, but the fix is
easy- the interface is still compatible, it was just gratuituously renamed
to match my arbitrary definition of consistency... VCBUS, the BCM2835 name,
represents an address on the VideoCore CPU Bus.

In a similar fashion, while it is a physical address, the ARMC portion
represents that these are addresses as seen by the ARM CPU.

To make things even more fun, the BCM2711 peripheral documentation describes
not virtual address space vs. physical address space, but instead the 32-bit
address map vs. the address map in "Low Peripheral" mode. The latter of
these is what the *ARMC* macros translate to/from.