tests: benchdnn: ip: regression: check tags matching

Co-authored-by: Dmitry Zarukin <dmitry.zarukin@intel.com>

tests/benchdnn/inputs/ip/harness_ip_regression

@@ -3,3 +3,9 @@
 
 # large oc to trigger use_buffer_b with tail
 --reset --dir=BWD_W mb32ic16oc2049_n"large_oc_for_use_buffer_b_with_tail"
+
+# f16->s8 is not supported by reference, gemm based ip handles this case,
+# but it requires src and weights to have compatible tags.
+# This test case makes sure ip chooses weights tag correctly for plain src tag
+# when shapes contain ones.
+--reset --dt=f16:f16:s8 --stag=abcd mb128ic768ih1oc768_n"f16_s8_plain_src_tag"