Increased mbox size to 256KB, ROM to 96KB and DCCM/ICCM to 256KB

[Nitsirks]

Increased MBOX size to 256KB
Moved direct access path to end of address map

Increased ROM to 96KB
Increased ICCM and DCCM to 256KB

Updated makefile and ld files to recognize larger memories

[calebofearth]

UVM reg model should also be updated:
Span: https://github.com/chipsalliance/caliptra-rtl/blob/user/dev/michnorris/mbox_params/src/soc_ifc/uvmf_soc_ifc/uvmf_template_output/verification_ip/environment_packages/soc_ifc_env_pkg/registers/soc_ifc_reg_model_top_pkg.sv#L887

Base addr: https://github.com/chipsalliance/caliptra-rtl/blob/user/dev/michnorris/mbox_params/src/soc_ifc/uvmf_soc_ifc/uvmf_template_output/verification_ip/environment_packages/soc_ifc_env_pkg/registers/soc_ifc_reg_model_top_pkg.sv#L1128

Base addr: https://github.com/chipsalliance/caliptra-rtl/blob/user/dev/michnorris/mbox_params/src/soc_ifc/uvmf_soc_ifc/uvmf_template_output/verification_ip/environment_packages/soc_ifc_env_pkg/registers/soc_ifc_reg_model_top_pkg.sv#L1134

[calebofearth]

Hardcoded address needs to be overridden:

caliptra-rtl/src/integration/tb/caliptra_top_tb_services.sv

Line 1463 in a3829e6

if (!hex_file_is_empty) $readmemh("mailbox.hex", dummy_mbox_preloader.ram,0,32'h0001_FFFF);