ext4: Allow GFP_FS allocations in ext4_da_convert_inline_data_to_extent()

Since commit 8bc1379b, the transaction is stopped before calling
ext4_da_convert_inline_data_to_extent(), which means we can do GFP_FS
allocations and recurse into the filesystem.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Theodore Ts'o <tytso@mit.edu>