arch/riscv: Fix the page table setup code

In particular:

- Fix the condition of the loop that fills the mid-level page table
- Adhere to the format of sptbr

Change-Id: I575093445edfdf5a8f54b0f8622ff0e89f77ccec
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/16120
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
1 file changed