MAINTAINERS: Update Atish's email address

I am no longer employed by western digital. Update my email address to
personal one and add entries to .mailmap as well.
Signed-off-by: Atish Patra <atishp@atishpatra.org>
Signed-off-by: Anup Patel <anup.patel@wdc.com>

.mailmap

@@ -50,6 +50,7 @@ Archit Taneja <archit@ti.com>
 Ard Biesheuvel <ardb@kernel.org> <ard.biesheuvel@linaro.org>
 Arnaud Patard <arnaud.patard@rtp-net.org>
 Arnd Bergmann <arnd@arndb.de>
+Atish Patra <atishp@atishpatra.org> <atish.patra@wdc.com>
 Axel Dyks <xl@xlsigned.net>
 Axel Lin <axel.lin@gmail.com>
 Bart Van Assche <bvanassche@acm.org> <bart.vanassche@sandisk.com>

MAINTAINERS

@@ -10445,7 +10445,7 @@ F:	arch/powerpc/kvm/
 
 KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv)
 M:	Anup Patel <anup.patel@wdc.com>
-R:	Atish Patra <atish.patra@wdc.com>
+R:	Atish Patra <atishp@atishpatra.org>
 L:	kvm@vger.kernel.org
 L:	kvm-riscv@lists.infradead.org
 L:	linux-riscv@lists.infradead.org