arm: mach-k3: Refactor QoS settings

arm: mach-k3: Refactor QoS settings

Refactor common QoS code into a new common header file, and the soc
specific setup_qos functions into a common API.

Rename $(soc)_qos_count and $(soc)_qos_data variables to qos_count and
qos_data. When QoS settings of more SoCs are added, only one pair will
be defined at a time, based on the config SOC_K3_$(soc).

This refactoring has been done for 2 major purposes.

- The auto-generated $(soc)_qos_data.c and $(soc)_qos.h files cannot
  have any code that is specific to any bootloader. Those files have to
  remain agnostic of different bootloader implementations and their
  header files.

- The existing implementation was less than ideal and would have enabled
  multiple $(soc)_qos_count and $(soc)_qos_data variables for all SoC
  variants.

Signed-off-by: Aradhya Bhatia <a-bhatia1@ti.com>