regmap: include <linux/delay.h> from include/linux/regmap.h

The readx_poll_timeout() macro calls usleep_range(), which is
declared in <linux/delay.h>.

Make include/linux/regmap.h include <linux/delay.h>, like
include/linux/iopoll.h does.  Otherwise, users of the macro
will see "implicit declaration of function 'usleep_range'" error.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: masahir0y

include/linux/regmap.h

@@ -15,6 +15,7 @@
 
 #include <linux/list.h>
 #include <linux/rbtree.h>
+#include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/bug.h>
 #include <linux/lockdep.h>