component: fix bug with legacy API

Sachin Kamat reports that "component: add support for component match
array" broke Exynos DRM due to a NULL pointer deref.  Fix this.

Reported-by: Sachin Kamat <sachin.kamat@samsung.com>
Tested-by: Sachin Kamat <sachin.kamat@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>