power: qpnp-qg: Clear learnt capacity on loading a new profile

Clear the learnt capacity (SDAM register) on loading a
new profile as the learning needs to be re-done with
the updated nominal capacity.

Change-Id: Ic249489bf378e98c960bdf05b95ce192ad63319b
Signed-off-by: Kavya Nunna <knunna@codeaurora.org>