package/gdb: remove stale hashes from GDB 10.x and 11.x

In commit 809fdb3a7a3e4da8e7734a0d7cec48a4b3b99ec5 ("package/gdb:
remove gdb 10.x") and
030497be18cfb4dfae6494ada0c202f6c7c0f5c0 ("package/gdb: remove support
for GDB 11.x"), we forgot to drop the no longer needed hashes from
gdb.hash. Let's do this now.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Romain Naour <romain.naour@smile.fr>

package/gdb/gdb.hash

@@ -1,6 +1,4 @@
 # From https://gcc.gnu.org/pub/gdb/releases/sha512.sum
-sha512  3653762ac008e065c37cd641653184c9ff7ce51ee2222ade1122bec9d6cc64dffd4fb74888ef11ac1942064a08910e96b7865112ad37f4602eb0a16bed074caa  gdb-10.2.tar.xz
-sha512  07e9026423438049b11f4f784d57401ece4e940570f613bd6958b3714fe7fbc2c048470bcce3e7d7d9f93331cdf3881d30dcc964cb113a071143a02b28e5b127  gdb-11.2.tar.xz
 sha512  8185d3e11ab60dafff5860a5016577bfe7dd7547ef01ebc867bc247603d82b74ff74c4f29492c7d2aee57076f52be33e289f4c6b414a4b870d4b3004909f4c34  gdb-13.2.tar.xz
 sha512  7e07941f1fe661288cc571b4964012ceabc1760624fce20320db2f470c01439b2386f859b5288da13204b758e2e3b22a74c68c012178db93b9529b06f1e22ede  gdb-14.2.tar.xz
 sha512  0217434073023a8b8316088bf3ee95d53a1b6a7897f6269095429016a8900f9a05e130c390d8d5d5550cc515c16519de1071d8eef96aa58e38056c7e37da1d8b  gdb-15.1.tar.xz