in many device attach paths, allocate memory with M_WAITOK instead of M_NOWAIT
and remove code to handle failures that can no longer happen.

branches: 1.5.38;
Change sdhc_detach so that it detaches all host controllers at once.
This should make multiple slot controllers, for example those with
a controller on more than one PCI/CardBus BAR, detach with fewer bugs.
Tested with as-of-yet-uncommited sdhc_pci changes on a single-host
ExpressCard JMicron JMB38[89].

branches: 1.4.6;
Use "opt_sdmmc.h" for SDHC_DEBUG.

branches: 1.3.2; 1.3.6;
remove some bloat:
-cardbus doesn't use multiple interrupt lines like PCI, and it doesn't
use machanisms like interrupt line register and swizzling -- no need
to carry around dummy information, this is all dealt with by the
bridge
(I'm asking myself how "rbus_ppb" can work -- a bridge attached to
cardbus just can't work like a normal PCI bridge as far as interrupts
are concerned. I thing that should be a hardware specific driver
because behavior is not covered by a standard.)
-cardbus always uses 3.3V -- no need for a variable to keep track
of the voltage

branches: 1.2.2;
Collect garbage: sc_rbus_{iot,memt} are not used.

branches: 1.1.2; 1.1.4;
Added sdhc at cardbus support.