mtd: fix musl build issue

With musl C library, we get following build error

  integck.c:37:28: fatal error: bits/stdio_lim.h: No such file or directory
   #include <bits/stdio_lim.h>
                              ^
  compilation terminated.
  make[2]: *** [integck] Error 1

Header <bits/stdio_lim.h> is not available in musl C library. However
<stdio.h> has all definition that <bits/stdio_lim.h> supposed to be
providing. Moreover <bits/stdio_lim.h> shouldn't be included directly
instead we should be using <stdio.h>.

Since we already include <stdio.h> and in case of uClibc or glibc
<bits/stdio_lim.h> gets included internally, we can safely remove it.

Fixes:

  http://autobuild.buildroot.net/results/175/1754861457af520480cc34d7d2d0edff2868ff66/



Signed-off-by: Rahul Bedarkar <rahul.bedarkar@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>