iwlwifi: mvm: assure no overflows occur while reading otp

Just in case sizes change in the OTP without proper SW
updating, an additional check is inserted when reading OTP
sections to assure no overflows occur.

Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>