Fix build of sparc64 kernel with newer toolchain

[bapt]

Summary

gcc 4.9.1 complains about parenthesis in
sys/dev/mc146818/mc146818.c
gas is not happy with the typo in support.S

[marius]

Looks like the proposed change for mc146818.c adds parentheses in the wrong spots, breaking intended semantics.
The proper variant (untested) should be:
if (!((*sc->sc_mcread)(dev, MC_REGD) & MC_REGD_VRT)) {
However, the best variant would be to re-write it FreeBSD-bit-checking-style, which translates to:
if (((*sc->sc_mcread)(dev, MC_REGD) & MC_REGD_VRT) == 0) {
There are two other lines in mc146818.c which should also be changed to FreeBSD-style then, though.

[bapt]

Use FreeBSD-bit-checking-style to appease gcc 4.9.1

[marius]

Looks good now

[bapt]

Closed by commit rS272894 (authored by @bapt).