devlink: Implement devlink param multi attribute nested data values

devlink: Implement devlink param multi attribute nested data values

Devlink param value attribute is not defined since devlink is handling
the value validating and parsing internally, this allows us to implement
multi attribute values without breaking any policies.

Devlink param multi-attribute values are considered to be dynamically
sized arrays of u64 values, by introducing a new devlink param type
DEVLINK_PARAM_TYPE_U64_ARRAY, driver and user space can set a variable
count of u64 values into the DEVLINK_ATTR_PARAM_VALUE_DATA attribute.

Implement get/set parsing and add to the internal value structure passed
to drivers.

This is useful for devices that need to configure a list of values for
a specific configuration.

example:
$ devlink dev param show pci/... name multi-value-param
name multi-value-param type driver-specific
values:
cmode permanent value: 0,1,2,3,4,5,6,7

$ devlink dev param set pci/... name multi-value-param \
		value 4,5,6,7,0,1,2,3 cmode permanent

Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Ratheesh Kannoth <rkannoth@marvell.com>
Link: https://patch.msgid.link/20260609040453.711932-5-rkannoth@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>