OPP: debugfs: Fix warning with W=1 builds

We currently get the following warning:

debugfs.c:105:54: error: '%d' directive output may be truncated writing between 1 and 11 bytes into a region of size 8 [-Werror=format-truncation=]
                 snprintf(name, sizeof(name), "supply-%d", i);
                                                      ^~
debugfs.c:105:46: note: directive argument in the range [-2147483644, 2147483646]
                 snprintf(name, sizeof(name), "supply-%d", i);
                                              ^~~~~~~~~~~
debugfs.c:105:17: note: 'snprintf' output between 9 and 19 bytes into a destination of size 15
                 snprintf(name, sizeof(name), "supply-%d", i);

Fix this and other potential issues it by allocating larger arrays.
Use the exact string format to allocate the arrays without getting into
these issues again.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202402141313.81ltVF5g-lkp@intel.com/


Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Dhruva Gole <d-gole@ti.com>