EDAC/skx_common: Make skx_dev->imc[] a flexible array

EDAC/skx_common: Make skx_dev->imc[] a flexible array

The current skx->imc[NUM_IMC] array of memory controller instances is
sized using the macro NUM_IMC. Each time EDAC support is added for a
new CPU, NUM_IMC needs to be updated to ensure it is greater than or
equal to the number of memory controllers for the new CPU. This approach
is inconvenient and results in memory waste for older CPUs with fewer
memory controllers.

To address this, make skx->imc[] a flexible array and determine its size
from configuration data or at runtime.

Suggested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20250731145534.2759334-5-qiuxu.zhuo@intel.com