Tegra194: mce: fix defects flagged by MISRA scan

Main fixes:

Added explicit casts (e.g. 0U) to integers in order for them to be
  compatible with whatever operation they're used in [Rule 10.1]

Fix variable essential type doesn't match [Rule 10.3]

Added curly braces ({}) around if/while statements in order to
  make them compound [Rule 15.6]

Voided non c-library functions whose return types are not used
  [Rule 17.7]

Change-Id: Iaae2ecaba3caf1469c44910d4e6aed0661597a51
Signed-off-by: Anthony Zhou <anzhou@nvidia.com>