efi_loader: Move .dynamic out of .text in EFI

efi_loader: Move .dynamic out of .text in EFI

EFI applications need to be relocatable. Ordinarily, this is achieved
through a PE-format .reloc section, but since that requires toolchain
tricks to achieve, U-Boot's EFI applications instead embed ELF-flavored
relocation information and use it for self-relocation; thus, the
.dynamic section needs to be preserved.

Before this patch, it was tacked on to the end of .text, but this was
not proper: A .text section is SHT_PROGBITS, while the .dynamic section
is SHT_DYNAMIC. Attempting to combine them like this creates a section
type mismatch. While GNU ld doesn't seem to complain, LLVM's lld
considers this a fatal linking error.

This patch moves .dynamic out to its own section, so that the output ELF
has the correct types. (They're all mashed together when converting to
binary anyway, so this patch causes no change in the final .efi output.)

Signed-off-by: Sam Edwards <CFSworks@gmail.com>
Cc: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>