vlynq: correct typo of missing "CONFIG_" prefix in ifdef

Fix a typo in the vlynq bus driver which was missing the CONFIG_ prefix to
turn on debugging code.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>