MAINTAINERS: update Tegra section to capture all Tegra files

The intent is to ensure that all Tegra-related patches are sent to the
linux-tegra@ mailing list, so people can keep up-to-date on all misc
driver changes.

Doing this with a keyword is far simpler and more compact than listing
all Tegra-related drivers, even if wildcards were used.

Words such as integrate or integrator are common.  Ensure the character
right before "tegra" isn't a-z (case-insensitive), to make sure the
keyword doesn't match those.

The only files that the keyword doesn't match are the NVEC driver.  Add
the linux-tegra mailing list to the NVEC entry to solve this.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Cc: Joe Perches <joe@perches.com>
Cc: Julian Andres Klode <jak@jak-linux.org>
Cc: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>