So, I solved the case, modified a couple of strings in /MYS6ULx-devel/fsl-release-yocto/sources/meta-fsl-bsp-release/imx/meta-bsp/recipes-kernel/linux/linux-imx_4.1.15.bb according to a new repository:
SRCBRANCH = "imx-4.1.15-1.0.0_ga"
SRCREV = "d5a63e0034a40833531d2adbb58c230efaa3a89c"
KERNEL_SRC ?= "git://source.codeaurora.org/external/imx/fsl-arm-yocto-bsp.git;protocol=git"
Also I removed patch URI, since it couldn't be installed (and shouldn't?). But then I have got another error. I'll create a new post.