module: Remove unused DISCARD_EH_FRAME definition from module.lds.S

The linker script scripts/module.lds.S contains an unused DISCARD_EH_FRAME
definition introduced by commit 68c76ad4a9 ("arm64: unwind: add
asynchronous unwind tables to kernel and modules").

As shown in an earlier version of that patch [1], DISCARD_EH_FRAME was
meant to be used by SANITIZER_DISCARDS in the same file, as follows:

-# define SANITIZER_DISCARDS	*(.eh_frame)
+# define SANITIZER_DISCARDS	DISCARD_EH_FRAME

However, in the meantime, SANITIZER_DISCARDS was removed entirely from
module.lds.S by commit 8924560094 ("cfi: Switch to -fsanitize=kcfi").
Eventually, the mentioned commit 68c76ad4a9 only added the new
DISCARD_EH_FRAME definition to this file without actually using it.

The file include/asm-generic/vmlinux.lds.h contains a similar
DISCARD_EH_FRAME definition for vmlinux to discard .eh_frame sections that
may be present when CONFIG_GCOV_KERNEL, CONFIG_KASAN_GENERIC or
CONFIG_KCSAN is enabled. Testing these options on arm64 with LLVM 19.1 did
not show any unexpected .eh_frame sections in modules.

Remove the unused DISCARD_EH_FRAME definition from scripts/module.lds.S.

Link: https://lore.kernel.org/linux-arm-kernel/20220701152724.3343599-2-ardb@kernel.org/ [1]
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>

scripts/module.lds.S

@@ -3,11 +3,6 @@
  * Archs are free to supply their own linker scripts.  ld will
  * combine them automatically.
  */
-#ifdef CONFIG_UNWIND_TABLES
-#define DISCARD_EH_FRAME
-#else
-#define DISCARD_EH_FRAME	*(.eh_frame)
-#endif
 
 #include <asm-generic/codetag.lds.h>