MAINTAINERS: Drop obsolete entries from Samsung sxgbe ethernet driver

The emails to ks.giri@samsung.com and vipul.pandya@samsung.com bounce
with 550 error code:

    host mailin.samsung.com[203.254.224.12] said: 550
    5.1.1 Recipient address rejected: User unknown (in reply to RCPT TO
    command)"

Drop Girish K S and Vipul Pandya from sxgbe maintainers entry.

Cc: Byungho An <bh74.an@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -14548,8 +14548,6 @@ F:	include/linux/platform_data/spi-s3c64xx.h
 
 SAMSUNG SXGBE DRIVERS
 M:	Byungho An <bh74.an@samsung.com>
-M:	Girish K S <ks.giri@samsung.com>
-M:	Vipul Pandya <vipul.pandya@samsung.com>
 S:	Supported
 L:	netdev@vger.kernel.org
 F:	drivers/net/ethernet/samsung/sxgbe/