imx: mx6: add display of CPU temperature grade in print_cpuinfo()

imx: mx6: add display of CPU temperature grade in print_cpuinfo()

When CONFIG_IMX6_THERMAL is defined print the CPU temperature grade info
along with the current temperature.

Before:
 CPU:   Temperature 42 C

After:
 CPU:   Automotive temperature grade (-40C to 125C) at 42C
 CPU:   Industrial temperature grade (-40C to 105C) at 42C
 CPU:   Extended Commercial temperature grade (-20C to 105C) at 42C

Cc: Stefan Roese <[email protected]>
Cc: Eric Nelson <[email protected]>
Cc: Heiko Schocher <[email protected]>
Cc: Nikita Kiryanov <[email protected]>
Cc: Jon Nettleton <[email protected]>
Cc: Jason Liu <[email protected]>
Cc: Ye Li <[email protected]>
Cc: Fabio Estevam <[email protected]>
Cc: Christian Gmeiner <[email protected]>
Cc: Markus Niebel <[email protected]>
Cc: Peng Fan <[email protected]>
Tested-by: Nikolay Dimitrov <[email protected]>
Signed-off-by: Tim Harvey <[email protected]>