MIPS: qi_lb60: remove custom u-boot.lds script

MIPS: qi_lb60: remove custom u-boot.lds script

Remove the board specific linker script. It is not
needed anymore, the unified MIPS linker script can
be used instead.

The qi_lb60 target produces a slightly different
image after the change than before. The value of
'num_got_entries' symbol is different:

    @@ -49,7 +49,7 @@
     801000b4:      80122d00        lb      s2,11520(zero)
     801000b8:      80123500        lb      s2,13568(zero)
     801000bc:      80123ef8        lb      s2,16120(zero)
    -801000c0:      00000139        0x139
    +801000c0:      00000136        tne     zero,zero,0x4

     801000c4 <in_ram>:
     801000c4:      8d0bfffc        lw      t3,-4(t0)

This is caused by the different placement of the
'__got_start' and '__got_end' symbols between the
board specific scrip and the unified script.

  board specific script:

        __got_start = .;
        .got  : { *(.got) }
        __got_end = .;

  unified script:
        .got  : {
                __got_start = .;
                *(.got)
                __got_end = .;
        }

Despite this difference, the resulting images are
functionally identical.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Cc: Xiangfu Liu <xiangfu@openmobilefree.net>