ARM: dts: mdm: Update compatible field for MDM9640 V2 TSENS

Fusemap address for reading the offset/slope requires a
distinction between v1/v2. Update compatible field for MDM9640
v2 tsens.

CRs-Fixed: 1008416
Change-Id: Iafb6f75cd0e944a501e0c29ae0d0a8f9771d2f04
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>