mrsas: unbreak i386 build

[alfredo]

Summary

Fixes i386 build broke by D26531

Test Plan

Test on powerpc64 at OSU (by @afscoelho_gmail.com)
Buildkernel on powerpc, i386, powerpc64, powerpc64le, amd4

[alfredo]

Book-E powerpc and i386 with PAE have a 64 bit bus_addr_t

[jhibbits]

sys/dev/mrsas/mrsas.c

2784–2785

Would it not work to only keep line 2788, and always do htole64() instead?

[alfredo]

use just htole64

[luporl]

Using only htole64() won't work in all cases.

Consider the following code running on a BE machine:

uint32_t u32 = 0x12345678;
uint64_t u64;

u64 = htole32(u32);
printf("0x%016lx\n", u64);
u64 = htole64(u32);
printf("0x%016lx\n", u64);

It will print the following:
0x0000000078563412
0x7856341200000000

So, using htole64() on a 32-bit value doesn't give the same result as htole32().

[jhibbits]

@luporl we want a LE 64-bit number here.

Putting the full address into the 'Words' field is the correct approach. (Accepted over IRC)