vchiq: Rename timer func so they do not conflict with linuxkpi

sx: retire SX_NOADAPTIVE

The flag is not used by anything for years and supporting it requires an
explicit read from the lock when entering slow path.

Flag value is left unused on purpose.

Sponsored by: The FreeBSD Foundation

vchiq: Use mallocarray() to provide kcalloc()

This means we now also provide integer overflow protection, like the
Linux kcalloc().

Stop including sys/types.h from arm's machine/atomic.h, fix the places
where atomic.h was being included without ensuring that types.h (via
param.h) was included first, as required by atomic(9).

Fix locking for VCHI driver by matching sleepable/non-sleepable APIs:

- Emulate Linux mutex API using sx(9) locks with only exclusive operations
instead of mutex(9), in Linux mutexes are sleepable.
- Emulate Linux rwlock_t using rwlock(9) instead of sx(9). rwlock_t
in Linux are spin locks

Fix build without INVARIANTS/INVARIANT_SUPPORT:
- Replace "emulation" of return in lmutex_lock_interruptible macros by
proper static/inline function.

Submitted by: Guy Yur

Import VCHI driver for Broadcom's VideoCore IV GPU

Differential Revision: D1753