FreeBSD: Ignore make_dev_s() errors.

[amotin]

Since errors returned by zvol_create_minor_impl() are ignored by the
common code, it is more convenient to ignore make_dev_s() errors there.
It allows, for example, to get device created for the zvol after later
rename instead of having it further stuck in half-created state.
zvol_rename_minor() already ignores those errors.

While there, switch from MAXPHYS to maxphys in FreeBSD 13+.

How Has This Been Tested?

# zpool create zzz nvd0p1
# zfs set volmode=dev zzz
# zfs create -V 1G zzz/1234567890123456789012345678901234567890123456789012345678901234567890
# ls -la /dev/zvol/zzz/
ls: /dev/zvol/zzz/: No such file or directory
# zfs rename zzz/1234567890123456789012345678901234567890123456789012345678901234567890 zzz/qqq
# ls -la /dev/zvol/zzz/
total 1
dr-xr-xr-x  2 root  wheel      512 15 июля  10:45 .
dr-xr-xr-x  3 root  wheel      512 15 июля  10:45 ..
crw-r-----  1 root  operator  0x7f 15 июля  10:45 qqq
# zfs destroy zzz/qqq
# ls -la /dev/zvol/zzz/
ls: /dev/zvol/zzz/: No such file or directory
# zpool destroy zzz

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.