Makefile: Don't mess with .text section location for selected arches

Makefile: Don't mess with .text section location for selected arches

Most of architectures have .text section situated in the very beginning
of U-Boot binary and thus it is very logical that CONFIG_SYS_TEXT_BASE
is used on final linkage step to specify where U-Boot gets linked to.

For that we pass the following construction to the LD:
---------------------------->8-----------------------
xxx-ld ...  -Ttext $(CONFIG_SYS_TEXT_BASE) ...
---------------------------->8-----------------------

But there could be exceptions. For example:
 1. In case of ARCv2 we want to put vectors table in its own section
    .ivt in front of .text section which means we need either add an
    offset to CONFIG_SYS_TEXT_BASE to compensate for .ivt or don't
    pass "-Ttext" to the LD at all and specify link base in linker
    script directly.

 2. Some architectures even though have .text section in the very
    beginning of the U-Boot image still use different symbols to
    specify link-base:
       * NIOS2: CONFIG_SYS_MONITOR_BASE (which I really like because
         that exactly what makes sense - where out image starts but not
         beginning of its .text section which just happened to match the
         whole image beginning)
       * EXTENSA: CONFIG_SYS_TEXT_ADDR
       * X86: Which doesn't use CONFIG_SYS_MONITOR_BASE in case of EFI
         otherwise sets explicit link base in u-boot.lds

I think that's good to allow for flexibility and don't require each and
every architecture or even platform to specify CONFIG_SYS_TEXT_BASE as well
as use it to set .text section location.

So let's only pass "-Ttext xxx" for those architectures who don't set
link-base explicitly in their linker scripts.

This patch iaddresses comments for previously sent
https://patchwork.ozlabs.org/patch/867540/.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>