soc: snps: nsim: arc_v: rename SOC configuration symbols

Rename SOC configuration symbols from generic names to more specific
ones that include the vendor and platform information. This improves
clarity and prevents potential naming conflicts.

Changes:
- SOC_SERIES_RMX -> SOC_SERIES_NSIM_ARC_V_RMX
- SOC_RMX100 -> SOC_NSIM_ARC_V_RMX100

Signed-off-by: Afonso Oliveira <afonsoo@synopsys.com>