rpm-pkg: Fix when current directory is a symlink

The better fix would be to stop using the parent directory (principle of
least surprise), but as long as we use it, use it consistently.

Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/scripts/package/Makefile b/scripts/package/Makefile
index 1b7eaea..006960e 100644
--- a/scripts/package/Makefile
+++ b/scripts/package/Makefile
@@ -28,7 +28,7 @@
 # Remove hyphens since they have special meaning in RPM filenames
 KERNELPATH := kernel-$(subst -,_,$(KERNELRELEASE))
 MKSPEC     := $(srctree)/scripts/package/mkspec
-PREV       := set -e; cd ..;
+PREV       := set -e; cd -P ..;
 
 # rpm-pkg
 # ---------------------------------------------------------------------------