lib: Remove redundant ftrace flag removal

Since architectures can implement ftrace using a variety of mechanisms,
generic code should always use CC_FLAGS_FTRACE rather than assuming that
ftrace is built using -pg.

Since commit:

  2464a609de ("ftrace: do not trace library functions")

... lib/Makefile has removed CC_FLAGS_FTRACE from KBUILD_CFLAGS, so ftrace is
disabled for all files under lib/.

Given that, we shouldn't explicitly remove -pg when building
lib/string.o, as this is redundant and bad form.

Clean things up accordingly.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Coly Li <[email protected]>
Cc: Gary R Hook <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

lib/Makefile

@@ -21,10 +21,6 @@ KCOV_INSTRUMENT_dynamic_debug.o := n
 ifdef CONFIG_AMD_MEM_ENCRYPT
 KASAN_SANITIZE_string.o := n
 
-ifdef CONFIG_FUNCTION_TRACER
-CFLAGS_REMOVE_string.o = -pg
-endif
-
 CFLAGS_string.o := $(call cc-option, -fno-stack-protector)
 endif