benchdnn: input: conv: enable ch_tail tests for F32 NXC DW Conv

Author: msotoflo

tests/benchdnn/inputs/conv/harness_conv_f32_nxc

@@ -4,10 +4,8 @@
 --stag=axb --dtag=axb
 --mb=2                      # for fwd and bwd_d reduce mb
 
---dir=FWD_B,BWD_D
+--dir=FWD_B,BWD_D,BWD_WB
 --batch=set_conv_all --batch=shapes_mobilenet_dw --batch=shapes_regression_dw
 
---dir=BWD_WB --batch=set_conv_all
-
 --mb=0                      # for bwd_w use the actual mb for 1 topology
 --dir=BWD_WB --batch=shapes_resnet_50