i2c: xiic: Record xilinx i2c with Zynq fragment

Include xilinx soft i2c controller to Zynq fragment to make clear who is
responsible for it.

Signed-off-by: Michal Simek <[e-mail]>
Signed-off-by: Wolfram Sang <[e-mail]>

MAINTAINERS

···
 F:	drivers/i2c/busses/i2c-cadence.c
 F:	drivers/mmc/host/sdhci-of-arasan.c
 F:	drivers/edac/synopsys_edac.c
+F:	drivers/i2c/busses/i2c-xiic.c
 
 ARM64 PORT (AARCH64 ARCHITECTURE)
 M:	Catalin Marinas <[e-mail]>