zlib: Fix build error when LOG_LEVEL=50

When enabling VERBOSE() traces, the zlib library fails to compile
because of an incompatible format specifier string. Fix that.

Change-Id: I74ff1c8dc2e6157ee982f7754bce4504599e3013
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
1 file changed