mk: fix custom kernel directory name

[ upstream commit a3549d2 ]

When building dpdk with different kernel headers by specifying
RTE_KERNELDIR igb_uio is compiled to directory with a name of the
version of kernel thats running on the system instead of the one that
dpdk is actually compiled against. Fixed by replacing hardcoded value
with value from RTE_KERNELDIR.

Fixes: 3967af3 ("mk: install kernel modules")

Signed-off-by: Herakliusz Lipiec <herakliusz.lipiec@intel.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>

mk/rte.sdkinstall.mk

@@ -24,7 +24,7 @@ export prefix ?=
 kerneldir   ?= $(prefix)/kmod
 else
 ifeq ($(RTE_EXEC_ENV),linuxapp)
-kerneldir   ?= /lib/modules/$(shell uname -r)/extra/dpdk
+kerneldir   ?= $(RTE_KERNELDIR:/build=/extra/dpdk)
 else
 kerneldir   ?= /boot/modules
 endif