kbuild: rpm-pkg: avoid the warnings with dtb's listed twice

After 8d1001f7bdd0 (kbuild: rpm-pkg: fix build error with CONFIG_MODULES=n),
the following warning "warning: File listed twice: *.dtb" is appearing for
every dtb file that is included.
The reason is that the commented commit already adds the folder
/lib/modules/%{KERNELRELEASE} in kernel.list file so the folder
/lib/modules/%{KERNELRELEASE}/dtb is no longer necessary, just remove it.

Fixes: 8d1001f7bdd0 ("kbuild: rpm-pkg: fix build error with CONFIG_MODULES=n")
Signed-off-by: Jose Ignacio Tornos Martinez <[e-mail]>
Reviewed-by: Nathan Chancellor <[e-mail]>
Tested-by: Nathan Chancellor <[e-mail]>
Signed-off-by: Masahiro Yamada <[e-mail]>

scripts/package/kernel.spec

···
 	done
 
 	if [ -d "%{buildroot}/lib/modules/%{KERNELRELEASE}/dtb" ];then
-		echo "/lib/modules/%{KERNELRELEASE}/dtb"
 		find "%{buildroot}/lib/modules/%{KERNELRELEASE}/dtb" -printf "%%%ghost /boot/dtb-%{KERNELRELEASE}/%%P\n"
 	fi