samples/bpf: Remove sample tracex2

In commit ba8de79 ("net: introduce sk_skb_reason_drop function")
kfree_skb_reason() becomes an inline function and cannot be traced.

samples/bpf is abandonware by now, and we should slowly but surely
convert whatever makes sense into BPF selftests under
tools/testing/selftests/bpf and just get rid of the rest.

Link: torvalds@ba8de79
Signed-off-by: Rong Tao <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: Rtoax

samples/bpf/Makefile

@@ -13,7 +13,6 @@ tprogs-y += sockex1
 tprogs-y += sockex2
 tprogs-y += sockex3
 tprogs-y += tracex1
-tprogs-y += tracex2
 tprogs-y += tracex3
 tprogs-y += tracex4
 tprogs-y += tracex5
@@ -63,7 +62,6 @@ sockex1-objs := sockex1_user.o
 sockex2-objs := sockex2_user.o
 sockex3-objs := sockex3_user.o
 tracex1-objs := tracex1_user.o $(TRACE_HELPERS)
-tracex2-objs := tracex2_user.o
 tracex3-objs := tracex3_user.o
 tracex4-objs := tracex4_user.o
 tracex5-objs := tracex5_user.o $(TRACE_HELPERS)
@@ -105,7 +103,6 @@ always-y += sockex1_kern.o
 always-y += sockex2_kern.o
 always-y += sockex3_kern.o
 always-y += tracex1.bpf.o
-always-y += tracex2.bpf.o
 always-y += tracex3.bpf.o
 always-y += tracex4.bpf.o
 always-y += tracex5.bpf.o