iwlwifi: mvm: add support for EWRD (Dynamic SAR) ACPI table

iwlwifi: mvm: add support for EWRD (Dynamic SAR) ACPI table

Dynamic SAR allows changing TX power limits at runtime to comply with
SAR regulations on multiple form factors (e.g. tablet vs. clamshell
mode).  To support this, a new table was added to ACPI, which is
called Extended Wireless Regulatory Descriptor (EWRD).  This table
allows OEMs to define different TX power profiles for each form-factor
or usage mode.

Read this new table and store it in our SAR profiles table, in
preparation for Dynamic SAR support.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>