generic: fix patching error on kernel 5.4

generic: fix patching error on kernel 5.4

Fixes a build error seen when applying the kernel patches.

Applying patch generic/435-mtd-add-routerbootpart-parser-config.patch
patching file drivers/mtd/parsers/Kconfig
Hunk #1 FAILED at 160.
1 out of 1 hunk FAILED -- rejects in file drivers/mtd/parsers/Kconfig
patching file drivers/mtd/parsers/Makefile
Hunk #1 FAILED at 10.
1 out of 1 hunk FAILED -- rejects in file drivers/mtd/parsers/Makefile

This was missed as 5.4 is currently set as testing kernel
while the main kernel being used is 4.19

Fixes: 2976e423dc6e ("generic: routerboot partition build bits")
Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>