ide: re-add TRM290 fix lost during ide_build_dmatable() cleanup

commit 14c123f37187aba0b4e0e893a969efc6820c4170 ("ide: cleanup
ide_build_dmatable()") accidentally reverted TRM290 fix introduced
by commit 22e05b4549bf2405d6aca128540b20cd2dd33f1f ("ide-dma: fix
ide_build_dmatable() for TRM290").

Reported-by: Sergei Shtylylov <sshtylyov@ru.mvista.com>
Acked-by: Sergei Shtylylov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-dma-sff.c

@@ -130,7 +130,7 @@ int ide_build_dmatable(ide_drive_t *drive, struct request *rq)
 			xcount = bcount & 0xffff;
 			if (is_trm290)
 				xcount = ((xcount >> 2) - 1) << 16;
-			if (xcount == 0x0000) {
+			else if (xcount == 0x0000) {
 				if (count++ >= PRD_ENTRIES)
 					goto use_pio_instead;
 				*table++ = cpu_to_le32(0x8000);