hw/arm/aspeed_ast27x0: Rename variable sram_name to name in ast2700 realize

hw/arm/aspeed_ast27x0: Rename variable sram_name to name in ast2700 realize

The variable "sram_name" was only used for naming the SRAM memory region.
Rename it to "name" for consistency with similar code and avoid unnecessary
new local variable declarations.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Tested-by: Nabih Estefan <nabihestefan@google.com>
Link: https://lore.kernel.org/qemu-devel/20250423072350.541742-2-jamin_lin@aspeedtech.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>