drivers: thermal: ddr_cdev: use cdev name within cdev max name length

Use ddr bus scaling cooling device name within max cooling device
name size limit.

Change-Id: I7ad370134a8875c3fc4edffd9941aec5fb09f4ca
Signed-off-by: Manaf Meethalavalappu Pallikunhi <manafm@codeaurora.org>