hwpmc_mod.c: whitespace style cleanup

[mhorne]

Summary

Handle a few things related to spacing:

• Remove redundant/superfluous blank lines (and add a couple where helpful)
• Add spacing around binary operators
• Remove spacing after casts and before goto labels
• Adjustments for line width of 80 chars
• Tab/space character issues

[jkoshy]

sys/dev/hwpmc/hwpmc_mod.c

1792

Consider keeping this blank line, as it visually separates exit processing steps from the rest of the function?

[jkoshy]

sys/dev/hwpmc/hwpmc_mod.c

4999

Consider keeping this blank line to preserve visual separation?

5327

Consider keeping this blank line, for better visual separation of exit processing from the rest of the function?