Fix various misspellings of:

 * deprecated
 * partition
 * preceding,preceded
 * preparation
 * its versus it's
 * export
 * existing
 * scenario
 * redundant
 * remaining
 * value
 * architecture

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Reviewed-by: Jagan Teki <jteki@openedev.com>
Reviewed-by: Stefan Roese <sr@denx.de>