optimise bootsector code

[coolgw]

After check this file, i find some garbage code, so i remove this part from the code.

[wjn740]

@aleksei-burlakov

[wjn740]

I run this patch in my environment. It's worked. so I think it is safe to merge.

[wjn740]

But it caused can't output e820 memory map on desktop. I don't know if it is root cause. I'm researching.

[wjn740]

jnwang@linux-g6xe: pts/5: 13 files 276Kb  ((8a6b11f...)|BISECTING)-> git bisect good
877cb03293a3df17884c874fdb183d1e88796dd4 is the first bad commit
commit 877cb03293a3df17884c874fdb183d1e88796dd4
Author: coolgw <wegao@suse.com>
Date:   Tue Feb 11 19:44:55 2020 +0800

    optimise bootsector code

 bsp/x86/bootsector.s    | 37 ++++++++-----------------------------
 bsp/x86/lowlevel_init.s |  4 ++--
 buildrules/linker.rules |  3 +++
 3 files changed, 13 insertions(+), 31 deletions(-)

[wjn740]

@coolgw unfortunately, it's a bad patch, it caused the e820 memory detector failure. Please take a look.

[coolgw]

@coolgw unfortunately, it's a bad patch, it caused the e820 memory detector failure. Please take a look.

fixed it now, you can try again.

[wjn740]

you need to review resolve conflicts.