xtensa: fix spelling mistake in Kconfig "wont" -> "won't"

There is a spelling mistake in the Kconfig help text. Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Message-Id: <20201217172427.58009-1-colin.king@canonical.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>