ti-soc-thermal: Use devm_kcalloc() in ti_bandgap_build()

A multiplication for the size determination of a memory allocation
indicated that an array data structure should be processed.
Thus use the corresponding function "devm_kcalloc".

This issue was detected by using the Coccinelle software.

Acked-by: Keerthy <j-keerthy@ti.com>
Tested-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>