usb_updater: fix command line options description
usb_updater: fix command line options description

The -b command line option should not be described as requiring a
parameter, as the binary file is given to most of invocations of
usb_updater.

Also adding the missing -p command line option description.

BRANCH=none
BUG=none
TEST='usb_updater -b <file name>' does not fail any more

Change-Id: I6ceefa8c4dda841db63177d6134a611600a43078
Signed-off-by: Vadim Bendebury <5515d6d2d0829cbe0dd0dcf2094aaded06d58514@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/448956
Reviewed-by: Aaron Durbin <af0622ab041e8b0f8e5819838dcc93898196e71f@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec