config: qemu: relax print and console buffer size

QEMU print and console buffer sizes have been restricted on QEMU below
their default values.

One of the side effects of the print buffer size restriction is output
truncation of the 'efidebug dh' command.

As QEMU does not have special memory size restrictions remove the settings
from the defconfig files and go with the generic defaults.

Fixes: d0ee7f29 ("Convert CONFIG_SYS_PBSIZE to Kconfig")
Fixes: d31466b3 ("Convert CONFIG_SYS_CBSIZE to Kconfig")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>