substitute kernel name in Makefile

use uname -r in Makefile to get the right kernel name when updating the
kernel of system

.SRCINFO

@@ -1,7 +1,7 @@
 pkgbase = yt6801-dkms
 	pkgdesc = Kernel module for Motorcomm YT6801 ethernet controller (DKMS)
 	pkgver = 1.0.28
-	pkgrel = 2
+	pkgrel = 3
 	url = https://deb.tuxedocomputers.com/ubuntu/pool/main/t/tuxedo-yt6801/
 	arch = x86_64
 	license = GPL-2.0-or-later

PKGBUILD

@@ -5,7 +5,7 @@
 _pkgbase=yt6801
 pkgname=yt6801-dkms
 pkgver=1.0.28
-pkgrel=2
+pkgrel=3
 pkgdesc="Kernel module for Motorcomm YT6801 ethernet controller (DKMS)"
 arch=('x86_64')
 url="https://deb.tuxedocomputers.com/ubuntu/pool/main/t/tuxedo-yt6801/"
@@ -28,6 +28,11 @@ package() {
   # Copy dkms.conf
   install -Dm644 dkms_filtered.conf ${pkgdir}/usr/src/${_fullname}/dkms.conf
 
+  sed -i -e "1i KERNELRELEASE ?= \$(shell uname -r)" \
+      -e "s|^KSRC = .*|KSRC = /lib/modules/\$(KERNELRELEASE)/build|" \
+      -e "s|^KDST = .*|KDST = /lib/modules/\$(KERNELRELEASE)/kernel/drivers/net/ethernet/motorcomm/|" \
+      Makefile
+
   # Copy sources (including Makefile)
   install -Dm644 ${srcdir}/*.c ${pkgdir}/usr/src/${_fullname}/
   install -Dm644 ${srcdir}/*.h ${pkgdir}/usr/src/${_fullname}/