ARM: meson: fix spelling mistake: "Couln't" -> "Couldn't"

Trivial fix to spelling mistake in pr_err error message

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>