xfs: dont cast to char * for XFS_DFORK_*PTR macros

Code in the next patch will assign the return value of XFS_DFORK_*PTR
macros to a struct pointer.  gcc complains about casting char* strings
to struct pointers, so let's fix the macro's cast to void* to shut up
the warnings.

While we're at it, fix one of the scrub tests that uses PTR to use BOFF
instead for a simpler integer comparison, since other linters whine
about char* and void* comparisons.

Can't satisfy all these dman bots.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_format.h

@@ -1008,7 +1008,7 @@ enum xfs_dinode_fmt {
  * Return pointers to the data or attribute forks.
  */
 #define XFS_DFORK_DPTR(dip) \
-	((char *)dip + xfs_dinode_size(dip->di_version))
+	((void *)dip + xfs_dinode_size(dip->di_version))
 #define XFS_DFORK_APTR(dip)	\
 	(XFS_DFORK_DPTR(dip) + XFS_DFORK_BOFF(dip))
 #define XFS_DFORK_PTR(dip,w)	\

fs/xfs/scrub/inode.c

@@ -556,7 +556,7 @@ xchk_dinode(
 	}
 
 	/* di_forkoff */
-	if (XFS_DFORK_APTR(dip) >= (char *)dip + mp->m_sb.sb_inodesize)
+	if (XFS_DFORK_BOFF(dip) >= mp->m_sb.sb_inodesize)
 		xchk_ino_set_corrupt(sc, ino);
 	if (naextents != 0 && dip->di_forkoff == 0)
 		xchk_ino_set_corrupt(sc, ino);