mmc: sunxi: Fix setup of last descriptor of dma transfer

The last descriptor might be the first descriptor as well, so use masking to
add the LD (last descriptor) bit and drop the DIC (disable interrupt on
completion) bit rather then hard assignment as hard assigment will override
the FD (first descriptor) bit if there is only 1 descriptor.

Also set the ER (end of ring) bit and clear buf_addr_ptr2 on the last
descriptor, like the android kernel code does.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: David Lanzendörfer <david.lanzendoerfer@o2s.ch>
Reported-by: 李想 <lixiang@allwinnertech.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
mmc: sunxi: Lock fix

1)	Adding a comment in order to clarify the choice of the locks within
	sunxi_mmc_handle_manual_stop

2)	As 李想 has pointed out the wait_dma variable was not accessed within the spin lock
	block in sunxi_mmc_request and so (even if it should never happend) it would have
	theoretically been possible that some other function would access the variable
	at the same time as the function.
	This has been changed now and the function is using local variables outside the lock
	and copys the value over during the lock phase.

Signed-off-by: David Lanzendörfer <david.lanzendoerfer@o2s.ch>
Reported-by: 李想 <lixiang@allwinnertech.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
mmc: sunxi: Correcting SDXC_HARDWARE_RESET bit

Fixing the register name in sunxi_mmc_reset_host since the SDXC_HARDWARE_RESET bit
is actually located within REG_GCTRL and not REG_CMDR as it was pointed out by Allwinner.

Signed-off-by: David Lanzendörfer <david.lanzendoerfer@o2s.ch>
Reported-by: 李想 <lixiang@allwinnertech.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
mmc: sunxi: Removing unused code

Removing a relict from reverse engineering of the Android driver code in
sunxi_mmc_clk_set_rate.

Signed-off-by: David Lanzendörfer <david.lanzendoerfer@o2s.ch>
Reported-by: 李想 <lixiang@allwinnertech.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>