x86/mce: Avoid unnecessary padding in struct mce_bank

Convert struct mce_bank member "init" from bool to a bitfield to get rid
of unnecessary padding.

$ pahole -C mce_bank arch/x86/kernel/cpu/mce/core.o

before:

  /* size: 16, cachelines: 1, members: 2 */
  /* padding: 7 */
  /* last cacheline: 16 bytes */

after:

  /* size: 16, cachelines: 1, members: 3 */
  /* last cacheline: 16 bytes */

No functional changes.

Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220225193342.215780-2-Smita.KoralahalliChannabasappa@amd.com