ext4: drop ext4_kvmalloc()

As Jan pointed out[1], as of commit 81378da64d ("jbd2: mark the
transaction context with the scope GFP_NOFS context") we use
memalloc_nofs_{save,restore}() while a jbd2 handle is active.  So
ext4_kvmalloc() so we can call allocate using GFP_NOFS is no longer
necessary.

[1] https://lore.kernel.org/r/20200109100007.GC27035@quack2.suse.cz

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20200116155031.266620-1-tytso@mit.edu
Reviewed-by: Jan Kara <jack@suse.cz>

fs/ext4/xattr.c

@@ -1456,7 +1456,7 @@ ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
 	if (!ce)
 		return NULL;
 
-	ea_data = ext4_kvmalloc(value_len, GFP_NOFS);
+	ea_data = kvmalloc(value_len, GFP_KERNEL);
 	if (!ea_data) {
 		mb_cache_entry_put(ea_inode_cache, ce);
 		return NULL;