arm: lib: Split asm symbols into different .text subsections

Split each symbol in lib1funcs into different .text.foo section instead
of placing all of them into plain .text . This allows the linker to collect
and discard unused assembler symbols.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: Tom Rini <trini@konsulko.com>