perf tools mips: Fix mips syscall generation

The mips syscall generation was still based on the old method. Delete
the Makefile since it is no longer needed with the new method of
generation.

Reported-by: Arnaldo Carvalho de Melo <[email protected]>
Fixes: 619ffe6 ("perf tools mips: Use generic syscall scripts")
Signed-off-by: Charlie Jenkins <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: charlie-rivos