spell: Kconfig help typos: /arch

Fix misspellings in Kconfig help text and made spelling of
RX and TX consistent (from reviewer comments)

Change-Id: Ie9d4c3863cd210e7a17b50a85a7e64156b6bf3d7
Signed-off-by: David B. Kinder <david.b.kinder@intel.com>
8 files changed