i2c: designware: Use PCI PSP driver for communication

Currently the PSP semaphore communication base address is discovered
by using an MSR that is not architecturally guaranteed for future
platforms.  Also the mailbox that is utilized for communication with
the PSP may have other consumers in the kernel, so it's better to
make all communication go through a single driver.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Mark Hasemeyer <markhas@chromium.org>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Mark Hasemeyer <markhas@chromium.org>
Acked-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>