Do not hardcode COMPRESSIONTYPES

Signed-off-by: Stefano Babic <stefano.babic@swupdate.org>

classes-recipe/swupdate.bbclass

@@ -51,7 +51,6 @@ do_package_write_ipk[noexec] = "1"
 do_package_write_deb[noexec] = "1"
 do_package_write_rpm[noexec] = "1"
 
-COMPRESSIONTYPES = ""
 PACKAGE_ARCH = "${MACHINE_ARCH}"
 
 INHIBIT_DEFAULT_DEPS = "1"