RFC: PCI SD host controller driver & mmc/mmcsd modules improvements

[Adam McDougall]

Oleksandr Tymoshenko wrote: 
> 7.1 requires s/kproc/kthread/ but otherwise works fine:
>
> sdhci0: <RICOH R5C822 SD> mem 0xff9fb800-0xff9fb8ff irq 9 at device 
> 1.2 on pci2
> sdhci0: 1 slot(s) allocated
> sdhci0: [ITHREAD]
>
> mmc0: <MMC/SD bus> on sdhci0
> mmc0: SD card: 507379712 bytes
> mmcsd0: 483MB <MMC/SD Memory Card> (read-only) at mmc0
> mmc0: setting transfer rate to 30.000MHz
> mmc0: setting bus width to 4 bits
It also works on my Dell Latitude E6500, I read and wrote some files in 7.1:

sdhci0: <RICOH R5C822 SD> mem 0xf65ff600-0xf65ff6ff irq 18 at device 1.2 
on pci3
sdhci0: 1 slot(s) allocated
sdhci0: [ITHREAD]
mmc0: <MMC/SD bus> on sdhci0
mmc0: setting transfer rate to 30.000MHz
mmcsd0: 968MB <MMC/SD Memory Card> at mmc0
mmc0: setting bus width to 4 bits
sdhci0 at pci0:3:1:2:    class=0x080501 card=0x024f1028 chip=0x08221180 
rev=0x21 hdr=0x00
    vendor     = 'Ricoh Company, Ltd.'
    device     = 'R5C832, R5C843 SDA Standard Compliant SD Host Controller'
    class      = base peripheral

Thanks!