configs/orange-pi-zero-plus2: bump kernel and u-boot versions

Bump versions:
- use U-Boot 2008.01
- use Linux kernel v4.15.2

Drop patch with dts sdcard fix since it has been
merged to Linux v4.15.

Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
2 files changed