ARM: dts: msm: support PM6150L BOB dynamic mode configuration on SM6150

Add support to allow consumers to dynamically control the mode of
PM6150L BOB at runtime.  Implement the following mapping for
pm6150l_bob load current requests:
Current (uA)    Active Mode    Sleep Mode
 >= 2000000        PWM            PWM
 >= 1000000        AUTO           PFM
  < 1000000        AUTO           PASS

Change-Id: Ia3a83a69b7b7b048a442e886055474eaf9fe9438
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>