ARM: tegra: defconfig updates

- ams AS3722 is used as system PMIC for Tegra124 based Venice2.
- NXP PCA9546 is used in Cardhu Tegra30 board to connect to 3 cameras.
- GSPCA to support the webcam on Venice2.
- Allocate 64 MiB for CMA by default; the default 16MiB is not enough
  for the majority of use-cases. This can still be overridden by the cma
  command-line option.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Bryan Wu <pengw@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>