kernel-devsrc: use the common NI kernel-devsrc.inc

The kernel-devsrc.bbappend currently uses its own implementation of the
NI-specific postinst methods. There already exists a
kernel-devsrc-nilrt.inc file which includes a more modern version of the
same function, and which is sourced by the alternative kernel-devsrc
packages.

Use the kernel-devsrc-nilrt.inc file which is common to all NILRT
kernel-devsrc implementations, in the primary version of the package,
for easier maintenance.

Signed-off-by: Alex Stewart <[email protected]>

recipes-kernel/linux/kernel-devsrc.bbappend

@@ -1,8 +1,4 @@
-pkg_postinst_ontarget_kernel-devsrc () {
-   cd /lib/modules/${KERNEL_VERSION}/build
-   make prepare
-   make modules_prepare
-}
+require kernel-devsrc-nilrt.inc
 
 # "make prepare" skips building objtool if elfutils-dev is not installed at
 # postinst time; however if you install elfutils-dev later, then when dkms