riscv: tools: Handle addend to absolute reloc in prelink-riscv

riscv: tools: Handle addend to absolute reloc in prelink-riscv

Previously the handling of R_RISCV_32 and R_RISCV_64 would simply
insert the value of the symbol and ignore any addend.  However, there
exist relocs where the addend is non-zero:

0000000080250900 R_RISCV_64        efi_runtime_services+0x0000000000000068
0000000080250910 R_RISCV_64        efi_runtime_services+0x0000000000000038
0000000080250920 R_RISCV_64        efi_runtime_services+0x0000000000000018
0000000080250930 R_RISCV_64        efi_runtime_services+0x0000000000000020
0000000080250980 R_RISCV_64        efi_runtime_services+0x0000000000000048
0000000080250990 R_RISCV_64        efi_runtime_services+0x0000000000000050
00000000802509a0 R_RISCV_64        efi_runtime_services+0x0000000000000058
0000000080250940 R_RISCV_64        systab+0x0000000000000030
0000000080250950 R_RISCV_64        systab+0x0000000000000040
0000000080250960 R_RISCV_64        systab+0x0000000000000050
0000000080250970 R_RISCV_64        systab+0x0000000000000060

In these cases the addend needs to be added to the symbol value to get
the correct value for the reloc.

Signed-off-by: Marcus Comstedt <marcus@mc.pp.se>
Cc: Rick Chen <rick@andestech.com>