KVM: riscv: selftests: Generate ISA extension reg_list using macros

Various ISA extension reg_list have common pattern so let us generate
these using macros.

We define two macros for the above purpose:
1) KVM_ISA_EXT_SIMPLE_CONFIG - Macro to generate reg_list for
   ISA extension without any additional ONE_REG registers
2) KVM_ISA_EXT_SUBLIST_CONFIG - Macro to generate reg_list for
   ISA extension with additional ONE_REG registers

This patch also adds the missing config for svnapot.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>