arm64: entry: fix KCOV suppression

We suppress KCOV for entry.o rather than entry-common.o. As entry.o is
built from entry.S, this is pointless, and permits instrumentation of
entry-common.o, which is built from entry-common.c.

Fix the Makefile to suppress KCOV for entry-common.o, as we had intended
to begin with. I've verified with objdump that this is working as
expected.

Fixes: bf6fa2c0dd ("arm64: entry: don't instrument entry code with KCOV")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210715123049.9990-1-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/kernel/Makefile

@@ -17,7 +17,7 @@ CFLAGS_syscall.o	+= -fno-stack-protector
 # It's not safe to invoke KCOV when portions of the kernel environment aren't
 # available or are out-of-sync with HW state. Since `noinstr` doesn't always
 # inhibit KCOV instrumentation, disable it for the entire compilation unit.
-KCOV_INSTRUMENT_entry.o := n
+KCOV_INSTRUMENT_entry-common.o := n
 KCOV_INSTRUMENT_idle.o := n
 
 # Object file lists.