kconfig: qconf: use delete[] instead of delete to free array

cppcheck reports "Mismatching allocation and deallocation".

$ cppcheck scripts/kconfig/qconf.cc
Checking scripts/kconfig/qconf.cc ...
scripts/kconfig/qconf.cc:1242:10: error: Mismatching allocation and deallocation: data [mismatchAllocDealloc]
  delete data;
         ^
scripts/kconfig/qconf.cc:1236:15: note: Mismatching allocation and deallocation: data
 char *data = new char[count + 1];
              ^
scripts/kconfig/qconf.cc:1242:10: note: Mismatching allocation and deallocation: data
  delete data;
         ^
scripts/kconfig/qconf.cc:1255:10: error: Mismatching allocation and deallocation: data [mismatchAllocDealloc]
  delete data;
         ^
scripts/kconfig/qconf.cc:1236:15: note: Mismatching allocation and deallocation: data
 char *data = new char[count + 1];
              ^
scripts/kconfig/qconf.cc:1255:10: note: Mismatching allocation and deallocation: data
  delete data;
         ^

Fixes: c4f7398b ("kconfig: qconf: make debug links work again")
Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>