selftests/powerpc/pmu: Link ebb tests with -no-pie

BugLink: https://bugs.launchpad.net/bugs/1812805

When running the ebb tests after building on a ppc64le Ubuntu machine:

 $ pmu/ebb/reg_access_test: error while loading shared libraries:
 R_PPC64_ADDR16_HI reloc at 0x000000013a965130 for symbol `' out of
 range

This is because the Ubuntu toolchain builds has PIE enabled by default.
Change it to be always off instead.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit 98415da)
Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Acked-by: Connor Kuehl <connor.kuehl@canonical.com>
Acked-by: Kleber Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

tools/testing/selftests/powerpc/pmu/ebb/Makefile

@@ -5,6 +5,9 @@ noarg:
 # The EBB handler is 64-bit code and everything links against it
 CFLAGS += -m64
 
+# Toolchains may build PIE by default which breaks the assembly
+LDFLAGS += -no-pie
+
 TEST_GEN_PROGS := reg_access_test event_attributes_test cycles_test	\
 	 cycles_with_freeze_test pmc56_overflow_test		\
 	 ebb_vs_cpu_event_test cpu_event_vs_ebb_test		\