udf: fix 3 signedness & 1 unitialized variable warnings

udf: fix 3 signedness & 1 unitialized variable warnings

sparse generated:
fs/udf/inode.c:324:41: warning: incorrect type in argument 4 (different signedness)
fs/udf/inode.c:324:41:    expected long *<noident>
fs/udf/inode.c:324:41:    got unsigned long *<noident>

inode_getblk always set 4th argument to uint32_t value
3rd parameter of map_bh is sector_t (which is unsigned long or u64)
so convert phys value to sector_t

fs/udf/inode.c:1818:47: warning: incorrect type in argument 3 (different signedness)
fs/udf/inode.c:1818:47:    expected int *<noident>
fs/udf/inode.c:1818:47:    got unsigned int *<noident>
fs/udf/inode.c:1826:46: warning: incorrect type in argument 3 (different signedness)
fs/udf/inode.c:1826:46:    expected int *<noident>
fs/udf/inode.c:1826:46:    got unsigned int *<noident>

udf_get_filelongad and udf_get_shortad are called always for uint32_t
values (struct extent_position->offset), so it's safe to convert offset
parameter to uint32_t

gcc warned:
fs/udf/inode.c: In function 'udf_get_block':
fs/udf/inode.c:299: warning: 'phys' may be used uninitialized in this function
initialize it to 0 (if someday someone will break inode_getblk we will catch it immediately)

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Ben Fennema <bfennema@falcon.csc.calpoly.edu>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>