fix(core): handle stack overflow on stm32f4 properly

[no changelog]

Co-authored-by: Copilot <copilot@github.com>

Author: cepetr

core/embed/sys/task/stm32/systask.c

@@ -790,9 +790,9 @@ __attribute__((naked, no_stack_protector)) void MemManage_Handler(void) {
       "MOV      R1, LR                \n"  // R1 = EXC_RETURN code
 #if !(defined(__ARM_ARCH_8M_MAIN__) || defined(__ARM_ARCH_8M_BASE__))
       "TST      LR, #0x4              \n"  // Return stack (1=>PSP, 0=>MSP)
-      "BEQ      1f                    \n"  // Skip stack ptr checking for PSP
+      "BNE      1f                    \n"  // Skip stack ptr checking for PSP
       "LDR      R2, =%[sstack]        \n"
-      "CMP      R0, R2                \n"  // Check if PSP is below the stack
+      "CMP      R0, R2                \n"  // Check if MSP is below the stack
       "ITT      LO                    \n"  // base
       "LDRLO    R2, =%[estack]        \n"
       "MSRLO    MSP, R2               \n"  // Reset MSP