zfs: Use grub_uint64_t instead of 1ULL in BF64_*CODE() macros

zfs: Use grub_uint64_t instead of 1ULL in BF64_*CODE() macros

The underlying type of 1ULL does not change across architectures but
grub_uint64_t does. This allows using the BF64_*CODE() macros as
arguments to format string functions that use the PRI* format string
macros that also vary with architecture.

Change the grub_error() call, where this was previously an issue and
temporarily fixed by casting and using a format string literal code,
to now use PRI* macros and remove casting.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>