kernel: Clean up KERNEL_IMAGETYPE_FOR_MAKE

Remove the lambda function setting KERNEL_IMAGETYPE_FOR_MAKE and instead
set it in the anonymous python function. This also allows us to handle
image types which are not supported directly by kernel, but require some
other kernel target to be built. This is the case for example with the
fitImage, which is the uImage successor.

There is no functional change.

(From OE-Core rev: a1690131691507bbf5853540229b3ad775b836bf)

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Richard Purdie <richard.purdie@linuxfoundation.org>
Cc: Koen Kooi <koen@dominion.thruhere.net>
Cc: Paul Eggleton <paul.eggleton@linux.intel.com>
Cc: Ross Burton <ross.burton@intel.com>
Cc: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/kernel.bbclass

@@ -17,12 +17,16 @@ INITRAMFS_TASK ?= ""
 INITRAMFS_IMAGE_BUNDLE ?= ""
 
 python __anonymous () {
+    import re
+
     kerneltype = d.getVar('KERNEL_IMAGETYPE', True)
     if kerneltype == 'uImage':
         depends = d.getVar("DEPENDS", True)
         depends = "%s u-boot-mkimage-native" % depends
         d.setVar("DEPENDS", depends)
 
+    d.setVar("KERNEL_IMAGETYPE_FOR_MAKE", re.sub(r'\.gz$', '', kerneltype))
+
     image = d.getVar('INITRAMFS_IMAGE', True)
     if image:
         d.appendVarFlag('do_bundle_initramfs', 'depends', ' ${INITRAMFS_IMAGE}:do_rootfs')
@@ -104,8 +108,6 @@ KERNEL_ALT_IMAGETYPE ??= ""
 # they are staged.
 KERNEL_SRC_PATH = "/usr/src/kernel"
 
-KERNEL_IMAGETYPE_FOR_MAKE = "${@(lambda s: s[:-3] if s[-3:] == ".gz" else s)(d.getVar('KERNEL_IMAGETYPE', True))}"
-
 copy_initramfs() {
 	echo "Copying initramfs into ./usr ..."
 	# In case the directory is not created yet from the first pass compile: