Tegra194: mce: fix multiple MISRA issues

This patch fixes violations of the following MISRA rules

* Rule 8.5  "An external object or function shall be declared once in
             one and only one file"
* Rule 10.3 "The value of an expression shall not be assigned to an
             object with a narrower essential type or of a different
             esential type category"

Change-Id: I4314cd4fea0a4adc6665868dd31e619b4f367e14
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>