ARM: dts: msm: Add external regulators in mpq8092

Add the following external regulators -

1. SMB210 external buck - switched on by PMIC PON sequence
2. SMB211 external buck - switched on by PMIC PON sequence
3. USB 3.0 OTG controlled by PM_GPIO 8
4. USB 2.0 OTG(Port-1) controlled by PM_GPIO 9
5. USB 2.0 OTG(Port-2) controlled by PM_GPIO 10

Change-Id: Id9c60f1442c959c7679475ce08c8dca218f63bba
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>