i2c: designware-baytrail: Disallow the CPU to enter C6 or C7 while holding the punit semaphore

On my cherrytrail tablet with axp288 pmic, just doing a bunch of repeated
reads from the pmic, e.g. "i2cdump -y 14 0x34" would lookup the tablet in
1 - 3 runs guaranteed.

This seems to be causes by the cpu trying to enter C6 or C7 while we hold
the punit bus semaphore, at which point everything just hangs.

Avoid this by disallowing the CPU to enter C6 or C7 before acquiring the
punit bus semaphore.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=109051


Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170210102802.20898-7-hdegoede@redhat.com