kernel: arm64: Added "model name" in /proc/cpuinfo

kernel: arm64: Added "model name" in /proc/cpuinfo

- Show "model name" in /proc/cpuinfo
- This will enable displaying processor info in
"System setting -> Details" in Ubuntu

model name display is generic.
model name      : ARMv8 Processor rev X (v8l)

bug 200225877

Change-Id: I6bd4334693b1e87c8f678f164be814d3047969ee
Signed-off-by: Ninad Malwade <nmalwade@nvidia.com>
Reviewed-on: http://git-master/r/1230761
Reviewed-by: Shreshtha Sahu <ssahu@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bibek Basu <bbasu@nvidia.com>