illumos gate

There are several typographical errors in both the manual pages and code comments. This change seeks to correct:

• inb(9F) & outb(9F) refer three times to ddi_put8(9F), et al, when they should rather refer to the three ddi_put*(9F) functions of increasing size.
• the LDI manual pages erroneously print ldi_callback_id_t as ldi_ev_callback_id_t.
• MPxIO is actually described in mdi_impldefs.h, not the (non-existant) mdi_impl.h.
• vdev_disk.c has a spelling error.