ARM: tegra: add KBC nodes to Tegra114 DT

NVIDIA's Tegra114 SoCs have the matrix keyboard controller which
supports 11x8 type of matrix. The number of rows and columns
are configurable.

Add DT entry for KBC controller with compatibility as "nvidia,tegra114-kbc".

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>