blk: Rework guard around part_init call

blk: Rework guard around part_init call

The function part_init() will only be built when we have both
CONFIG_PARTITIONS and CONFIG_HAVE_BLOCK_DEVICE set.  Protect the call to
this function with both of these tests now.

Cc: Simon Glass <sjg@chromium.org>
Cc: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: York Sun <york.sun@nxp.com>
Cc: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
Cc: Mingkai Hu <mingkai.hu@nxp.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Marek Behún <marek.behun@nic.cz>
Cc: Vanessa Maegima <vanessa.maegima@nxp.com>
Cc: Eugen Hristev <eugen.hristev@microchip.com>
Cc: Adam Ford <aford173@gmail.com>
Cc: Jagan Teki <jagan@amarulasolutions.com>
Cc: Tom Warren <twarren@nvidia.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Vitaly Andrianov <vitalya@ti.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>