bpf, doc: Add BPF JIT for RV32G to BPF documentation

Update filter.txt and admin-guide to mention the BPF JIT for RV32G.

Co-developed-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Björn Töpel <bjorn.topel@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20200305050207.4159-4-luke.r.nels@gmail.com

Documentation/admin-guide/sysctl/net.rst

@@ -67,7 +67,8 @@ two flavors of JITs, the newer eBPF JIT currently supported on:
   - sparc64
   - mips64
   - s390x
-  - riscv
+  - riscv64
+  - riscv32
 
 And the older cBPF JIT supported on the following archs:
 

Documentation/networking/filter.txt

@@ -606,7 +606,7 @@ before a conversion to the new layout is being done behind the scenes!
 
 Currently, the classic BPF format is being used for JITing on most
 32-bit architectures, whereas x86-64, aarch64, s390x, powerpc64,
-sparc64, arm32, riscv (RV64G) perform JIT compilation from eBPF
+sparc64, arm32, riscv64, riscv32 perform JIT compilation from eBPF
 instruction set.
 
 Some core changes of the new internal format: