src/acpi: add function gen: if_lgreater_ and namestr assignment

src/acpi: add function gen: if_lgreater_ and namestr assignment

1. add functions to generate if greater than conditions:
acpigen_write_if_lgreater_op_op:
   if (op1 > op2)
acpigen_write_if_lgreater_op_int:
   if (op > val)
acpigen_write_if_lgreater_namestr_int:
   if (namestr > val)
2. add function to assignal value to a namestr
 acpigen_write_store_namestr_to_op:
   namestr = val

TEST=Use above functions and check the generated SSDT table after OS
boot.

Signed-off-by: Cliff Huang <cliff.huang@intel.com>
Change-Id: Iffe1b23362a7ab58bdc2aa8daf45cd6f086ee818
Reviewed-on: https://review.coreboot.org/c/coreboot/+/72825
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Reviewed-by: Jérémy Compostella <jeremy.compostella@intel.com>
Reviewed-by: Anil Kumar K <anil.kumar.k@intel.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>