MAINTAINERS: bpf: Add Lehui and Puranjay as riscv64 reviewers

Lehui and Puranjay have been active RISC-V 64-bit BPF JIT
contributors/reviewers for a long time!

Let's make it more official by adding them as reviewers in
MAINTAINERS.

Thank you for your hard work!
Signed-off-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/r/20240405123352.2852393-1-bjorn@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

MAINTAINERS

@@ -3764,6 +3764,8 @@ X:	arch/riscv/net/bpf_jit_comp64.c
 
 BPF JIT for RISC-V (64-bit)
 M:	Björn Töpel <bjorn@kernel.org>
+R:	Pu Lehui <pulehui@huawei.com>
+R:	Puranjay Mohan <puranjay@kernel.org>
 L:	bpf@vger.kernel.org
 S:	Maintained
 F:	arch/riscv/net/