davinci: clean up inconsistent usage of spaces in Kconfig

In arch/arm/mach-davinci/Kconfig, some of the configuration
items are indented with multiple spaces instead of tabs.

Also, in couple of places, two spaces are used in the middle
of help text where one should do.

This patch fixes both issues.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>