This patch fix the following GCC warning:

../tools/intel_reg.c: In function ‘dump_decode’:
../tools/intel_reg.c:203:41: warning: ‘snprintf’ output may be truncated
before the last format character [-Wformat-truncation=]
   snprintf(decode, sizeof(decode), "\n%s", bin);
[..]
../tools/intel_reg.c:200:40: warning: ‘%s’ directive output may be
truncated writing up to 1023 bytes into a region of size 1022
[-Wformat-truncation=]
    snprintf(decode, sizeof(decode), " (%s)\n%s", tmp, bin);
[..]
../tools/intel_reg.c:200:4: note: ‘snprintf’ output between 5 and 2051
bytes into a destination of size 1024
    snprintf(decode, sizeof(decode), " (%s)\n%s", tmp, bin);
[..]

The decode[] variable contains concatenated contents of bin[] and tmp[],
both of which are allocated as 1024 bytes.

Allocating 1024 chars for bin[] seems like an overkill, since all it
ever holds it the output of to_binary().

to_binary outputs fixed format:
--------------------------------------------------------------------
               24               16                8                0
  1 1 0 1 1 1 1 0  1 0 1 0 1 1 0 1  1 0 1 1 1 1 1 0  1 1 1 0 1 1 1 1
--------------------------------------------------------------------
Which is 138 chars long (sans the new line).

We can limit the size of char bin[] to that number (-ish), and then
slightly bump the size of decode[] to accommodate for combined sizes of
tmp[] and bin[].

Changes since V1:
 - Improve commit message
Changes since V2:
 - updated commit message
 - limit the amount of stack abuse

Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Reviewed-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>