arm: socfpga: remove CONFIG_SYS_BOOTMAPSZ

socfpga_common.h defines CONFIG_SYS_BOOTMAPSZ to 64 MiB.

Since having this define overrides the 'bootm_size' env variable for
the whole socfpga platform, let's remove this define from socfpga_common.h
and instead rely on the 'bootm_size' env variable (which is initialized
to 160 MiB in the same file's default env). This gives users the
chance to override it in their own environment.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Acked-by: Marek Vasut <marex@denx.de>
Series-to: Marek Vasut <marex@denx.de>
Series-to: u-boot@lists.denx.de
Cover-letter:
arm: socfpga: clean up socfpga_common.h
This series cleans up the include/configs/socfpga_common.h file a bit.

It removes some defines that are used nowhere and cleans up some
leftovers after various subsystems have been converted to use DM.
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