*spec file update to build output uImage and Device Tree

*spec file update to build output uImage and Device Tree

The following changes have been implemented:
1. A new linux-kernel-uImage package was added. The package provide kernel uImage.
2. Additional cleanup linux-kernel-sources and linux-kernel-build packages
   was added.
3. Symbolic links linux-kernel-build-current and linux-kernel-sources-current were
   added. Links points current kernel sources and build directories.

Change-Id: Ifa889d42fca69cce4d458d9ac7e0514cfdf1caef
Signed-off-by: Jacek Pielaszkiewicz <j.pielaszkie@samsung.com>