intel_idle: Remove unused driver version constant

intel_idle: Remove unused driver version constant

The INTEL_IDLE_VERSION constant has not been updated since 2020 and serves
no useful purpose. The driver version is implicitly defined by the kernel
version, making this constant redundant.

Remove the constant to eliminate potential confusion about version
tracking.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Link: https://patch.msgid.link/20251215111229.132705-1-dedekind1@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>