modpost: zero-pad CRC values in modversion_info array

I do not think the '#' flag is useful here because adding the explicit
'0x' is clearer. Add the '0' flag to zero-pad the CRC values.

This change gives better alignment in the generated *.mod.c files.
There is no impact to the compiled modules.

[Before]

  $ grep -A5 modversion_info fs/efivarfs/efivarfs.mod.c
  static const struct modversion_info ____versions[]
  __used __section("__versions") = {
          { 0x907d14d, "blocking_notifier_chain_register" },
          { 0x53d3b64, "simple_inode_init_ts" },
          { 0x65487097, "__x86_indirect_thunk_rax" },
          { 0x122c3a7e, "_printk" },

[After]

  $ grep -A5 modversion_info fs/efivarfs/efivarfs.mod.c
  static const struct modversion_info ____versions[]
  __used __section("__versions") = {
          { 0x0907d14d, "blocking_notifier_chain_register" },
          { 0x053d3b64, "simple_inode_init_ts" },
          { 0x65487097, "__x86_indirect_thunk_rax" },
          { 0x122c3a7e, "_printk" },

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>