occamy: Improve readability of SRAM configuration type names

[paulsc96]

Actually, maybe we can call the occamy_cluster_pkg::sram_cfgs_t something like occamy_cluster_pkg::sram_cluster_cfgs_t and the occamy_pkg::sram_cfgs_t something like occamy_pkg::sram_occamy_cfgs_t?

Originally posted by @GiannaP in pulp-platform/snitch#303 (comment)