ARM: dts: msm: Rename the PMIC DT files and DT nodes

Rename the PMIC device tree files and nodes as below.
"pm640"  =====> pm6150
"pm640l" =====> pm6150l

Change-Id: I8e57f24abbebf8ae9fe56369a7d2d53042c44c77
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>