Some of the I2C bus drivers can be compile tested to increase build
coverage.  This requires also:
1. Adding dependencies on COMMON_CLK for BCM2835 and Meson I2C
   controllers,
2. Adding 'if' conditional to 'default y' so they will not get enabled
   by default on all other architectures,
3. Limiting few compile test options to supported architectures (which
   provide the readsX()/writesX() primitives).

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
[wsa: revert chunk for ZX2967. it needs more preparation]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>