power: pm8xxx-ccadc: remove support for pm8921 v1.0 and v1.1

This ccadc module is reused in multiple pmics. It is now unnecessary
to check for 8921 versions in the driver. As a result of this change
older 8921 versions are not supported.

CRs-Fixed: 372679
Change-Id: I2114f9428e2ba1a29c2bc9caaaa75106caf1dfc3
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>