ARM: dts: msm: Fix cx_cdev label size for MDM9607

Reducing the size of the node for rpm_requests to rpmb,
To fix probe error for node cx_cdev.

Change-Id: I08dfea19ea9d90dddc243db2410fcc72e74facb0
Signed-off-by: Sagar Chormale <schormal@codeaurora.org>
Signed-off-by: Sivasri Kumar Vanka <sivasri@codeaurora.org>