power: pm8921-charger: Allow disabling of input current limit

Some use cases require higher input currents which are out of range
of USB specification.

Fix this by adding a call to disable the input current limit and
warn the user with an adequate message that input current limiting
is disabled when the function is called

CRs-Fixed: 318511
Change-Id: I7e2baa0378c94b0b9af22c00d8605b9df8d4f826
Signed-off-by: David Keitel <dkeitel@codeaurora.org>