MAINTAINERS: Update Jisheng's email address

I'm leaving synaptics. Update my email address to my korg mail
address and add entries to .mailmap as well to map my work
addresses to korg mail address.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Link: https://lore.kernel.org/r/ce7213bd-28ac-6580-466e-875e755fe0ae@synaptics.com

'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>