packagegroups: delete useless "PROVIDES" lines

There is apparently no functional value to "PROVIDES" lines anymore in
packagegroup recipe files, so remove the lonely couple of examples
left.

(From OE-Core rev: 6f2c9602bc5fc6794b852ec20f40ea62a55ada1e)

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/packagegroups/packagegroup-base.bb

@@ -8,7 +8,6 @@ PACKAGE_ARCH = "${MACHINE_ARCH}"
 
 inherit packagegroup
 
-PROVIDES = "${PACKAGES}"
 PACKAGES = ' \
             packagegroup-base \
             packagegroup-base-extended \

meta/recipes-core/packagegroups/packagegroup-core-nfs.bb

@@ -7,7 +7,6 @@ PR = "r2"
 
 inherit packagegroup
 
-PROVIDES = "${PACKAGES}"
 PACKAGES = "${PN}-server ${PN}-client"
 
 SUMMARY_${PN}-client = "NFS client"