msm: spm: Update spm device tree for L2 command sequences

The SPM device tree entry to configure L2 SAW doesn't distinguish
between Krait and L2 SAW low power modes. Update the device tree to
differentiate between L2 and Krait low power modes.

Change-Id: I6c7cf6f8dd10478fd53826e22b17ed98d46b68b4
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>