x86/resctrl: Read supported bandwidth sources from CPUID

If the BMEC (Bandwidth Monitoring Event Configuration) feature is
supported, the bandwidth events can be configured. The maximum supported
bandwidth bitmask can be read from CPUID:

  CPUID_Fn80000020_ECX_x03 [Platform QoS Monitoring Bandwidth Event Configuration]
  Bits    Description
  31:7    Reserved
   6:0    Identifies the bandwidth sources that can be tracked.

While at it, move the mask checking to mon_config_write() before
iterating over all the domains. Also, print the valid bitmask when the
user tries to configure invalid event configuration value.

The CPUID details are documented in the Processor Programming Reference
(PPR) Vol 1.1 for AMD Family 19h Model 11h B1 - 55901 Rev 0.25 in the
Link tag.

Fixes: dc2a3e85

 ("x86/resctrl: Add interface to read mbm_total_bytes_config")
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
Link: https://lore.kernel.org/r/669896fa512c7451319fa5ca2fdb6f7e015b5635.1705359148.git.babu.moger@amd.com