x86/boot: Fix bootinfo.h to be standalone

x86/boot: Fix bootinfo.h to be standalone

Work to rebase the Trenchboot patch series has encountered:

  In file included from ./arch/x86/include/asm/tpm.h:4,
                   from arch/x86/boot/../tpm.c:23:
  ./arch/x86/include/asm/bootinfo.h:88:35: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'next_boot_module_index'
     88 | static inline unsigned int __init next_boot_module_index(
        |

Fix this by including the necessary header.

Fixes: 74af2d98276d ("x86/boot: eliminate module_map")
Reported-by: Krystian Hebel <krystian.hebel@3mdeb.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
Reviewed-by: Daniel P. Smith <dpsmith@apertussolutions.com>