board: relocate SafeXcel firmware selection to Marvell BSPs

The MVEBU SafeXcel Crypto Engine firmware (linux-firmware minifw) was
originally added in 70c12c3 to the generic aarch64 defconfigs to silence
kernel probe failures on Marvell Armada SoCs (37xx, 7k, 8k, CN913x):

  crypto-safexcel f2800000.crypto: Firmware load failed.
  crypto-safexcel f2800000.crypto: HW init failed (-2)

It was then accidentally dropped in 0e2d12e (kernel upgrade to 6.18),
which rebased on a tree that predated the firmware addition.

Rather than restoring it to the generic defconfigs, move it to the two
Marvell board Config.in files where it actually belongs — consistent
with how RTL8169 firmware was handled for the Raspberry Pi CM4 IoT
Router Board Mini in 68313773.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

board/aarch64/alder-alder/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_ALDER_ALDER
 	bool "Alder"
 	depends on BR2_aarch64
+	select BR2_PACKAGE_LINUX_FIRMWARE_INSIDE_SECURE_MINIFW
 	help
 	  Alder

board/aarch64/marvell-cn9130-crb/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_MARVELL_CN9130_CRB
 	bool "Marvell CN9130-CRB"
 	depends on BR2_aarch64
+	select BR2_PACKAGE_LINUX_FIRMWARE_INSIDE_SECURE_MINIFW
 	help
 	  Customer Reference Board for CN9130

board/aarch64/marvell-espressobin/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_MARVELL_ESPRESSOBIN
 	bool "Marvell ESPRESSObin"
 	depends on BR2_aarch64
+	select BR2_PACKAGE_LINUX_FIRMWARE_INSIDE_SECURE_MINIFW
 	help
 	  Marvell ESPRESSObin

board/aarch64/styx-dcp-sc-28p/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_STYX_DCP_SC_28P
 	bool "Styx DCP-SC-28P"
 	depends on BR2_aarch64
+	select BR2_PACKAGE_LINUX_FIRMWARE_INSIDE_SECURE_MINIFW
 	help
 	  Styx DCP-SC-28P