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/sifive_unleashed_defconfig b/configs/sifive_unleashed_defconfig
index f9f0346..f99ce30 100644
--- a/configs/sifive_unleashed_defconfig
+++ b/configs/sifive_unleashed_defconfig
@@ -29,7 +29,7 @@
 CONFIG_SPL_MAX_SIZE=0x100000
 CONFIG_SPL_BSS_START_ADDR=0x85000000
 # CONFIG_SPL_SHARES_INIT_SP_ADDR is not set
-CONFIG_SYS_SPL_MALLOC=y
+CONFIG_SPL_SYS_MALLOC=y
 CONFIG_SPL_DM_SPI_FLASH=y
 CONFIG_SPL_DM_RESET=y
 CONFIG_SPL_SPI_LOAD=y