efi_loader: Rename sections to allow for implicit data

Some times gcc may generate data that is then used within code that may
be part of an efi runtime section. That data could be jump tables,
constants or strings.

In order to make sure we catch these, we need to ensure that gcc emits
them into a section that we can relocate together with all the other
efi runtime bits. This only works if the -ffunction-sections and
-fdata-sections flags are passed and the efi runtime functions are
in a section that starts with ".text".

Up to now we had all efi runtime bits in sections that did not
interfere with the normal section naming scheme, but this forces
us to do so. Hence we need to move the efi_loader text/data/rodata
sections before the global *(.text*) catch-all section.

With this patch in place, we should hopefully have an easier time
to extend the efi runtime functionality in the future.

Signed-off-by: Alexander Graf <agraf@suse.de>
[agraf: Fix x86_64 breakage]