spl: Use CONFIG_SPL... instead of CONFIG_..._SPL_...

We like to put the SPL first so it is clear that it relates to SPL. Rename
various malloc-related options which have crept in, to stick to this
convention.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Martyn Welch <martyn.welch@collabora.com>
Reviewed-by: Svyatoslav Ryhel <clamor95@gmail.com>
diff --git a/configs/pico-nymph-imx7d_defconfig b/configs/pico-nymph-imx7d_defconfig
index 2cd906a..613ed6c 100644
--- a/configs/pico-nymph-imx7d_defconfig
+++ b/configs/pico-nymph-imx7d_defconfig
@@ -25,7 +25,7 @@
 CONFIG_SPL_MAX_SIZE=0xe000
 CONFIG_SPL_HAS_BSS_LINKER_SECTION=y
 CONFIG_SPL_BSS_MAX_SIZE=0x100000
-CONFIG_SYS_SPL_MALLOC=y
+CONFIG_SPL_SYS_MALLOC=y
 CONFIG_SYS_MAXARGS=32
 CONFIG_SYS_PBSIZE=532
 # CONFIG_CMD_BOOTD is not set