mmc: core: warn when card doesn't support HPI

Someone could use send_hpi_cmd() on a card that doesn't advertise support
for HPI.  Then maybe didn't work fine.  Because card->ext_csd.hpi_cmd
didn't set.  So if card didn't support hpi, return the warning message.

And CMD12's flags is MMC_RSP_R1B.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>