Tegra186: mce: fix MISRA defects

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]
* Force operands of an operator to the same type category [Rule 10.4]
* Added curly braces ({}) around if/while statements in order to
  make them compound [Rule 15.6]
* Added parentheses [Rule 12.1]
* Voided non C-library functions whose return types are not used [Rule 17.7]

Change-Id: I91404edec2e2194b1ce2672d2a3fc6a1f5bf41f1
Signed-off-by: Anthony Zhou <anzhou@nvidia.com>
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>