swupdate-enc: Convert CONVERSION_CMD to new override syntax

Convert CONVERSION_CMD to the new override syntax.

Converted with the help of poky/scripts/contri/convert-overrides.py.

Signed-off-by: Fabio Estevam <festevam@denx.de>

classes/swupdate-enc.bbclass

@@ -20,4 +20,4 @@ swu_encrypt_file() {
 CONVERSIONTYPES += "enc"
 
 CONVERSION_DEPENDS_enc = "openssl-native coreutils-native"
-CONVERSION_CMD_enc="swu_encrypt_file ${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type} ${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type}.enc"
+CONVERSION_CMD:enc="swu_encrypt_file ${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type} ${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type}.enc"