Add attribute 188 Command_Timeout to raw check list

[Napsty]

According to Blackblaze's statistics (https://www.backblaze.com/blog/what-smart-stats-indicate-hard-drive-failures/), the following five SMART attributes are good/helpful indicators of a failing drive:

• 5 (Reallocated Sectors Count)
• 187 (Reported Uncorrectable Errors)
• 188 (Command Timeout)
• 197 (Current Pending Sector Count)
• 198 (Uncorrectable Sector Count)

The current raw list (hard coded in the plugin, can be overwritten using the -r parameter) checks the following attributes on their raw values:

https://github.com/Napsty/check_smart/blob/master/check_smart.pl#L183

my $raw_check_list = $opt_r // 'Current_Pending_Sector,Reallocated_Sector_Ct,Program_Fail_Cnt_Total,Uncorrectable_Error_Cnt,Offline_Uncorrectable,Runtime_Bad_Block,Reported_Uncorrect,Reallocated_Event_Count';

Attribute 188 Command_Timeout is missing here and should be added.

[Napsty]

Added in version 6.8.0.