packages: use SPDX short identifier for zlib license

We want to use SPDX identifier for license string as much as possible.
SPDX short identifier for zlib license is Zlib.

This change is done using following command.
find . -name "*.mk" | xargs sed -ri '/LICENSE( )?[\+:]?=/s/zlib( )?(license)?/Zlib/g'

Signed-off-by: Rahul Bedarkar <rahulbedarkar89@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
diff --git a/package/tinyxml/tinyxml.mk b/package/tinyxml/tinyxml.mk
index df7b29f..1528051 100644
--- a/package/tinyxml/tinyxml.mk
+++ b/package/tinyxml/tinyxml.mk
@@ -10,7 +10,7 @@
 # configure.ac which is not present in mainline.
 TINYXML_AUTORECONF = YES
 TINYXML_INSTALL_STAGING = YES
-TINYXML_LICENSE = zlib
+TINYXML_LICENSE = Zlib
 TINYXML_LICENSE_FILES = README
 
 $(eval $(autotools-package))