integrity: remove unneeded, broken attempt to add -fshort-wchar

integrity: remove unneeded, broken attempt to add -fshort-wchar

I guess commit 15ea0e1e3e18 ("efi: Import certificates from UEFI Secure
Boot") attempted to add -fshort-wchar for building load_uefi.o, but it
has never worked as intended.

load_uefi.o is created in the platform_certs/ sub-directory. If you
really want to add -fshort-wchar, the correct code is:

  $(obj)/platform_certs/load_uefi.o: KBUILD_CFLAGS += -fshort-wchar

But, you do not need to fix it.

Commit 8c97023cf051 ("Kbuild: use -fshort-wchar globally") had already
added -fshort-wchar globally. This code was unneeded in the first place.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>