selftests: bpf: relax sub-register mode compilation criteria

Sub-register mode compilation was enabled only when there are eBPF "v3"
processor supports at both compilation time inside LLVM and runtime inside
kernel.

Given separation betwen build and test server could be often, this patch
removes the runtime support criteria.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/Makefile

@@ -28,12 +28,11 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 BPF_OBJ_FILES = $(patsubst %.c,%.o, $(notdir $(wildcard progs/*.c)))
 TEST_GEN_FILES = $(BPF_OBJ_FILES)
 
-# Also test sub-register code-gen if LLVM + kernel both has eBPF v3 processor
-# support which is the first version to contain both ALU32 and JMP32
-# instructions.
+# Also test sub-register code-gen if LLVM has eBPF v3 processor support which
+# contains both ALU32 and JMP32 instructions.
 SUBREG_CODEGEN := $(shell echo "int cal(int a) { return a > 0; }" | \
 			$(CLANG) -target bpf -O2 -emit-llvm -S -x c - -o - | \
-			$(LLC) -mattr=+alu32 -mcpu=probe 2>&1 | \
+			$(LLC) -mattr=+alu32 -mcpu=v3 2>&1 | \
 			grep 'if w')
 ifneq ($(SUBREG_CODEGEN),)
 TEST_GEN_FILES += $(patsubst %.o,alu32/%.o, $(BPF_OBJ_FILES))