x86/rtc: Remove unused intel-mid.h

The rtc driver used to be disabled with a direct check for Intel MID
platforms.  But that direct check was replaced long ago (see second
link).  Remove the (unused since 2016) include.

[ dhansen: rewrite changelog to include some history ]

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20240305161024.1364098-1-andriy.shevchenko%40linux.intel.com
Link: https://lore.kernel.org/all/1460592286-300-5-git-send-email-mcgrof@kernel.org